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Don't try the rest— come to the best!
Q2
1EAMLINH VKWDtI\
m m limited m m
230/6, Derby Road,Stapleford, Nottingham NG9 7BL Tel: Nottingham (0602) 396976
Acorn User
The official magazine for users of the Acorn Atom, the BBC microcomputer system,
and the Econet system, published by Addison-Wesley for Acorn Computers Limited.
• Authoritative information on all new Acorn products
• AH the latest software reviewed, including the products of Acornsoft
• New peripheral equipment described and tested, including unofficial items
• Feature articles on the latest developments in microcomputing from the UK, Europe. North America
the Far East, and Australasia
• Dealer and service features
• National and international user group news
Use the form below to make sure of your regular copies now!
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Direct Subscriptions
Please open one year's subscription to Acom User.
Annual subscription rates (please tick appropriate box):
□ UK £1 5 DEurope £18 □ Middle East £20
□ The Americas & Africa £22 DAII other countries £24
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delivery of Acorn User must be the same as the address
to which your credit card account is sent.
Send this form, with your remittance, to the address
overleaf.
Acorn User
The official magazine for users of the Acorn Atom, the BBC microcomputer system,
and the Econet system, published by Addison-Wesley for Acorn Computers Limited.
• Authoritative information on alt new Acorn products
• All the latest software reviewed, including the products of Acornsoft
• New peripheral equipment described and tested, including unofficial items
• Feature articles on the latest developments in microcomputing from the UK, Europe, North America
the Far East, and Australasia
• Dealer and service features
• National and international user group news
Use the form below to make sure of your regular copies now!
Acorn User
MAGSUB (Subscription Services) Ltd
Ground Floor Post Room
Oakfield House
Perrymount Road
HAYWARDS HEATH
West Sussex
RH16 3DH
Acorn User
MAGSUB (Subscription Services) Ltd
Ground Floor Post Room
Oakfield House
Perrymount Road
HAYWARDS HEATH
West Sussex
RH16 3DH
CONTENTS
ACORN
USER
Monthly
SEPTEMBER 1982, NUMBER TWO
Managing Editor
Jane Fransella
Editor
Tony Quinn
Sub-editor
Ann Nimmo
Production
Susie Home
Promotion Manager
Pat Bitton
Editorial Secretary
Jane Lake
Publisher
Stanley Malcolm
Typesetters and
Designers
GMGraphics
Graphic Designer
Phil Kanssen
Printed in Great Britain
by E.T. Heron & Co. Ltd.
Editorial
01-631 1636
Advertising Agents
Dealer Deals Ltd
20 Orange Street
London WC2H 7ED
01-930 1612
Published by
Addison-Wesley
Publishers Limited
53 Bedford Square
London WC1 B 3DZ
Telephone: 01-631 1636
Telex: 881 1948
ISSN: 201-17002 7
f Addison-Wesley
Publishers Ltd 1982
Subscription Information
For UK Subscriptions, send
your cheque or postal order
made payable to Addison-
Wesley Publishers Ltd to:
MAGSUB (Subscription Services)
Ltd. Ground Floor Post Room
Oakfieid House
Perrymount Road
Haywards Heath
West Sussex RH16 3DH
Annual subscripton rates,
UK £15
Europe £18
Middle East £20
The Americas and Africa £22
Rest of the World £24
2 Editorial
3 News
8 Acorn on show
Personal computer exhibition in London's
Barbican Centre.
10 Latest from the BBC
Telesoftware and the User Guide.
13 Business
The BBC micro can play a useful role, say
JohnTurnbull and John Gordon.
19 BBC or Spectrum?
Paul Beverley gives an unbiased review of
the pros and cons.
24 NEC 30 Hour Basic
Richard Freeman explains the course and
how it came about.
27 Art on screen
Brian Reffin Smith leads the way and hands
out some ideas.
31 Hints and tips
Joe Telford conducts the sound of music
from his keyboard.
36 Atom in action
Disk pack commands.
BBC Basic conversion board.
41 Bugged by ULAs
Andy Hopper explains how these chips go
wrong.
How to submit articles
You are welcome to submit articles to the Editor of Acorn User for publication. Acorn
User cannot undertake to return them unless a stamped addressed envelope is
enclosed. Articles should be typed or computer written. Black and white photographs
or transparencies are also appreciated. If submitting programs please send a
cassette or disc. Listings should not contain more than 39 characters per line for ease
of reproduction. Payment is £50 per page or pro rata. Please indicate if you have
submitted your article elsewhere.
Send articles reviews, and information to:
The Editor. Acorn User, 53 Bedford Square, London WC1 3DZ
44 Teletext graphics
Paul Carpenter and
Graham Field show
how to save on memory.
49 Machine code graphics II
John Shawand Anthony Ferguson
continue their probe.
52 Schools
Ian Carpenter plugs analogue in.
Pam Fiddy on teachers' problems.
56 Puzzles
Simon Daily's prize teaser.
58 User Groups
59 Atom graph fitting
60 Letters
62 Dealer list
Front cover: Brian Reffin Smllh produced
this piece ol art using the drawing package
Jackson, at the Royal College ol An m
London (see article page 27).
See next month's Acorn User for:
• Communication by micro across the
world • Red/gi
een/blue decoder for
the Atom
• Speech from the Beeb • Tips on the pitch
envelope and moving
graphics
• BBC paddles • Printing gi
'aphics • Book
reviews • Computer
crime
Alt rights reserved. No pan of this publication may be reproduced without prior written permission of the publisher The publisher
cannot accept any responsibility for errors in articles, programs or advertisements published. The opinions expressed on the
pages of this lournai are those of the authors and do not necessairly represent those ol the publisher. Acorn Computers Ltd. or
Acornsoit Ltd.
Acorn, Acornsoft. and the Acorn symbol are the registered trademarks ol Acorn Computers Ltd and AcornsoH Ltd.
DITORIAI
In the second issue of Acorn User, the official,
monthly magazine for users of Acorn products, we
bring you more authoritative, official and accurate
information. We include items for potential business
users, musicians and code breakers - to name but a
few. Whatever your interests we cater for them.
'«sem
SENSES""-
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Independent hardware reviews
We publish an independent review of the BBC micro
and the Spectrum. We felt this would be of interest to
readers as so many extravagant claims have been
made about the Spectrum. In our view, the BBC micro
is a much more powerful machine and is a wiser buy
for anyone with a serious interest in microcomputers.
Readers' letters
Letters and telephone calls have poured in from
readers all over the world. We like to hear from you,
but bear with us if you have not yet received a reply.
Keep on sending your queries, comments, hints and
tips or complaints. A selection of letters will be
published every month.
C
'^
t"JS.
r ^'o rs
Atom users
We have been inundated with complaints from Atom
buffs that they were neglected in the first issue of
Acorn User. Greater emphasis was given to the BBC
micro but given the topicality of the machine at the
time and the number of unresolved issues, I think we
can be forgiven because the Atom is a well
established micro. We have included more on the
Atom in this issue and will continue to do so. We
would particularly welcome contributions from Atom
enthusiasts for consideration for publication.
BBC
The BBC will be making regular contributions, and
this month we have articles from John Radcliffe, David
Allen and Meyer Solomon of the Computer Literacy
Project. See page 10 for details of the BBC's
telesoftware plans. We also have news from BBC
Publications about their software.
Acorn User competition
Entries to our first competition have come flooding in.
Look out for the results in the October issue of Acorn
User. This month's competition is on page 56.
PCW Show
We will make our presence felt at the Personal
Computer World Show at the Barbican Centre in
London, September 9-12. You'll find us on stand 444
in Hall B (upper). Acorn Computers will be there and
there will be a separate dealer arcade (page 8). See
you there!
fl-
*e
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25?««*.4,
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*• "»-o»*
Official dealers
For those needing servicing and upgrading facilities,
we would advise you to consult the official dealers list
on page 62. Each month we wil carry an update.
Software and books
You are invited to submit your programs and books
for review. Future issues will carry substantial
coverage of all products related to Acorn computers.
User groups
Each month we will list user groups which have come
to our notice (page 58). If you are running a group let
us know.
Contributors
If you have any articles, hints or programs - we're
ready and waiting! Articles should be typed or
computer written, with black and wnite photographs,
or colour transparencies. When submitting programs
please send a cassette or disc with a full printed
listing.
one
fva^j^M^
Managing Editor
ACORN USER SEPTEMBER
NEWS
Hauser hits
at Sinclair
campaign
ACORN director Hermann
Hauser has attacked
Sinclair's comparison ad-
vertising campaign in the
computer press.
Hauser described the
six page insert as 'unfair
and incorrect' and said he
was considering taking
the matter up with the
Advertising Standards
Authority - who have
already had several
complaints about other
Sinclair promotions.
The main query was
Sinclair's claim: 'What
may not be so obvious is
that it also provides more
power.' This claim is
made in direct com-
parison to the BBC model
A.
Hauser"s reply was:
'Whichever way you
measure it the BBC
computer is more powerful
than the ZX Spectrum.
'The first measure of
power is benchmarks -
and the BBC model A is
three to five times faster
than the Spectrum.'
The benchmarks are
widely used in the
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The offending table
from a recent computer
magazine- contains eight changes
*-*-s^s
S^aphfci
computer industry and
quoted in magazines.
Another incorrect asser-
tion was that the
maximum RAM for the
BBC model A micro was
32 k.
In fact it can go up to
96k when a second
processor is added, said
Hauser.
He added that the
model A could give eight
colours, that the display
ran up to 32 not 25
columns, and that it did
provide VERIFY and
MERGE statements, but
under a different name.
The advertisement also
gave the impression that
the model did not provide
user-definable graphics.
And close analysis of
the insert shows that it
Acorn drops hints on Electron
The Electron will be in
the price range of the
Spectrum, but out
perform the Apple -
that's the confident
prediction from Acorn.
The company is
unwilling to release any
specification or photo-
graphs of their new
machine as they feel it
would spoil the launch.
Their spokesmen are
talking in terms of a
December release - but
even that is not definite.
Acorn have, however,
And prototype
microfloppy 'for
£100' on test
let lip that they are
working on prototypes
of a full facility 3 1 /2''
micro-floppy for their
computers. And they
forecast a price tag
of under £100.
This compares with
Sinclair's much vaunted
-but not yet seen -
Microdrive which is
advertised as 'available
later this year, for
around £50.'
However, several
'Sinclair-watchers 1 have
said this is unlikely to
be a proper microdrive
as it may not have a
random access facility
and will be more like a
fast cassette, without
the full advantages of a
floppy disc.
Nobody is giving any-
thing away at Acorn on
test results, or a release
date -but we'll let you
know.
has had several alterations.
The insert marked
'PCW807' had no less
than eight changes
compared to that marked
'COT806*.
However, Sinclair's ad-
vertising agency Primary
Contact defended the
insert. Spokesman Chris
Fawkes said: The in-
formation has been
correct as far as we can
check. It was provided by
our client Sinclair.'
He admitted receiving
a complaint about the
insert from the ASA, to
which he had replied.
Changes had been made
since it came out in June
and a third version
produced.
On the subject of
power, he said it was a
difficult comparison to
make and that bench
tests were the most
independent assessments.
But, he added, Sinclair
had clarified his claim by
referring to the RAM
provided.
ACORN USER SEPTEMBER
NEWS
Weetabix troubleshooters
aid distribution handover
THE BBC's new distri-
bution system for its
micros was due to be in
action from today.
Vector marketing, an
Acorn subsidiary, has
taken over from BL
Marketing at Kettering.
John Radcliffe, exec-
utive producer of the
BBC Computer Literacy
Project said there had
been 'a few teething
problems', but that
these were being dealt
with.
The change, said Mr
Radcliffe, was because
of 'a very heavy volume
of calls and letters which
strained the BLM system
beyond its capacities'.
He hoped the new
distribution organisation
with its computer record
system would provide a
good service for the
'disgruntled users - or
would-be users' of BBC
micros.
Maths, science
English and
Lisp programs
EDUCATION programs
on simple science,
maths and English are
now available on cassette
and disc for the BBC
micro .
The science programs
cover speed, time and
distance; properties of
light; electric current
theory and Archimedes'
principle. Maths theory
covered is addition,
subtraction and division,
while the language
program tackles sentence
construction, word se-
quencing and spelling.
All three are produced
by Acornsoft, with prices
starting from £8.65 per
cassette and £13.65 per
disc.
The list processing
language Lisp has been
adapted for the Atom
and the Beeb-
Acornsoft and Owl
Computers developed
the interpreter which is
provided on cassette at
£1 7.25 for the Atom, and
£16.85 for the Beeb,
both including VAT. The
books - Lisp Theory and
Practice (£6) and Lisp on
the BBC Microcomputer
(£7.50) - were written as
introductions.
Cassettes and books
are available through
dealers, or from Acornsoft
direct at 4a Market Hill,
Cambridge CB2 3NJ.
Any help for Denis?
DENIS Thatcher and his two friends look a bit
non-plussed by whatever their BBC micro is up to.
The students are from South Downs College near
Havant where the Prime Minister announced the
Government's £9m subsidy for micros in primary
schools. The date for Mrs Thatcher's brave new
world, when all primary and secondary schools
will have micros is 1984. Perhaps it was that
ominous date which was worrying our intrepid
trio. (Turn to page 54 for a picture of the PM in
action.)
Vector have installed
a computer to deal with
the operation and plan
to use BBC micros as
terminals with purpose-
written software.
Weetabix - BLM's
parent company
appointed a 'trouble
shooting' team to ensure
the handover to Vector
was as gremlin-free as
possible.
Customers with out-
standing orders for
micros and peripherals
should have received a
letter giving a new order
number. Please quote
this with any enquiries.
Vector spokesman.
Peter Goater, said the
new Alpha computer was
working 'very well indeed',
but added that delivery
delays couldn't be
solved until the pro-
duction backlog was
filled.
The new address will be
Vector Marketing, Dening-
ton Industrial Estate.
Wellingborough, Northants,
NN8 2RL Tel: Welling-
borough (0933) 79300
Dealer tests
TEST equipment for the
BBC machines is now in
production, says Acorn.
The final inspection
tester (FIT) and the
progressive establish-
ment tester (PET) will
both be offered to
dealers at £80 and £200
respectively.
Learning with simple listings
TEN programs to help
you explore the potential
of the BBC micro are
contained in Learning
with the Beeb, by Eric
Deeson. It is aimed
specifically at educational
users and produced by
AVC Software, who have
up to now sold software
for the Sinclair range.
The longest listing is
46 lines and the level of
program varies from
primary/remedial to 1 6-
plus physics, although
most can be played by
children of any age.
Games include a reflex
tester, train race, bar
chart, graph, projectile
simulation - and even a
simple version of Logo.
The booklet costs
£2.50 in the UK, and is
50 p dearer elsewhere.
Members of Muse,
Beebug and Ezug can
buy it for £2.
Details from AVC Soft-
ware, PO Box 415,
Harborne. Birmingham B17
9TT.
ACORN USER SEPTEMBER 1982
FOR THE BEST
SOFTWARE
So why not try our mail order service.
EIEETPSEN
For Model A or B, real time
advanced Startrek Game.
Extra facilities include "probe satellites",
"damage reports" & "on-board computer".
£795
J.R.
Cobra/Robo-Swamp ^ ^f
For Model A or B (please state
version required). Two addictive
£k#j Qp graphic games -
l/O.^/O insomniacs delight!
fi
For Model B only. Two player game,
features include exploration, drilling,
employment and e±g± g\^
Price Wars. £0.95
For Model A or B Jfl I rlljria*
Accepts up to ten definable fields.
Facilities include Quick Search, Sort
and Hard copy — capable of storing up
to 300 complete records
in memory (Model B).
£9.95
lumv.
For Model A or B. Classic Arcade
game. With colour and sound.
£6.95
K&
Character Generator
For Model B only. Useful utility programme
enables user to re-define character set
using Mode 4. Displays new character
in graph form.
£4.95
We are looking for good
quality programs covering games,
utilities and education on the BBC Micro. We pay
excellent royalty rates. Please write or phone us on
Dealer enquiries also welcome. (0708) 60725
Please send me:-
•\
72 NORTH STREET,
ROMFORD, ESSEX.
TEL 0708 60725
BMCLAVtARD
I enclose Cheque/P.O. for - £
Please debit my
Access/Barclaycard No.
; ; | 1
Name
Address
Make cheques/P.O. payable to: SOFTWARE FOR ALL
72 North Street, Romford, Essex.
V.
Tel: Romford (0708) 60725
AU2
ACORN USER SEPTEMBER
NEWS
John Radcttfte of (he BBC
Telesoft
receiver
details
PRODUCTION of the
telesoftware receiver is
due to start next month at
Acorn in Cambridge.
The BBC estimates it
has received 1200 orders
for receivers, and is
hoping for 5000 within
the next year. And the
Corporation is already
transmitting a telesoft-
ware magazine REM on
page 705 of Ceefax.
The 'magazine' is nine
pages long and gives
news about the BBC
micro. It is updated every
two weeks, (see page 10
Acorn User).
Teletext is called using
the command 'TELETEXT,
and channels can be
switched by typing *BBC1 ,
-BBC2 or*ITV.
The display will be 25
lines high, leaving the
bottom line free for
message or commands to
be typed in.
Software for trans-
mission has been written
by the Government's
Microelectronics Educa-
tion Programme, Acorn-
soft and the BBC.
John Radcliffe, exec-
utive producer of the BBC
Computer Literary Project,
sees a great future for
telesoftware.
The only problem, he
said, was finding some
way of funding it as in its
present form it is free to
users. And the BBC
cannot, of course, carry
advertising on the service.
For more news, see pages
10 and 11.
£9m primary school
micro subsidy set to go
THE Government's £9m
scheme to provide micro-
computers in every primary
school by 1984 will start
from next month.
Primary spending on any
of three chosen systems
will be matched by the
Department of Industry.
The price to schools
includes a cassette recorder
training material, mono-
chrome TV with the option
of a colour monitor.
Two of the packages are
similar to those offered to
secondary schools - the
BBC Acorn Model B C540,
(colour monitor £110 extra)
and the Research Machines
Link 480Z (£818 plus
£104). The third system is
the Sinclair Spectrum at
£346 (plus £126).
This scheme is an
extension of the secondary
scheme, started last April,
and the Government believes
it is 'well on target' in its
aim of seeing a micro in
every secondary school. So
far, 5200 have been
provided between the 6000
schools - although the
Department of Industry
believes every secondary
school now has at least one
micro.Application should be
made through local educa-
tion authorities, who have
been provided with details
for the school year's start.
Second TV series
THE BBC has announced
the dates for transmission
of their second computer
series - Make the Most of
Your Micro.
The ten programmes are
scheduled to start on BBC
1 on Sunday January 9 and
will run until March 13. The
broadcast time will be
12.35 to 1.00 pm, with
repeats on Mondays from
3.05 to 3.30 pm. The series
will again be shown late at
night on Mondays in May.
Meanwhile, the first
series will be repeated on
BBC 1, Sundays 12.35 to
1 .00 pm from October 1 to
December 12; again on
Mondays 3.05 to 3.30 pm
on BBC 2 from October 1 1
to December 13.
Another series Micros in
Education will be broadcast
on Monday afternoons 3.30
to 3.55 pm on BBC 2 from
February 13 to March 14
and repeated on Sunday
mornings BBC 1 in May.
BBC software
review to start
Acorn User is to begin a
major software review
section. All programs for
BBC micros - A and B -
will be studied and
assessed by an inde-
pendent panel of experts.
No matter how small
or large your programs
are, whether you write
them at weekends or for
the BBC, if they are sold
we will review them.
The software can be
directed at any market -
games, educational, bus-
iness, word processing.
Please include standard
packaging and instruc-
tions with tapes, as well
as price list.
Send your cassettes
or discs to Software
Review Editor, Acorn
User, 53 Bedford Square,
London WC1 B 3DZ.
The sooner we receive
your contribution, the
sooner we can review it
and assess it for our
readers.
Cassette lead
THE diagrams on
wiring up the BBC
micro cassette interface
on page 14 of July's
Acorn User are correct.
However, one part
looks into the wire
while the other part
looks out. So follow
the numbers, then you
can't go wrong. Pin
numbers are stamped
on the insulation of
the DIN plug.
New Guides
REVISED User Guides
are now being delivered
and everyone should
have them within the
next week, says the
BBC. Over 9,000 were
despatched in the first
week of August, and
the BBC had taken
delivery of almost all
copies. The delay in
sending them out was
apparently caused by
difficulties with ring
binding.
BBC soft
AUNTIE has jumped
into the software
market with eight
cassettes for the BBC
micros. They cover
home finance, early
learning, games of
strategy, fun games,
painting, drawing, music
and programs from the
Computer Programme.
Each costs £10 from
BBC Publications.
ACORN USER SEPTEMBER
RF1GLIR CDmPUTER CEnTRE
MICROCOMPUTER SPECIALISTS FOR BUSINESS AND SCIENCE
88 ST. BENEDICT'S STREET
NORWICH NR2 4AB
TELEPHONE: (0603) 29652, 26002 TELEX: 975 201
A SPECIAL
OFFER
^CORN
COMPUTER
^^S£gg&g£§
Ifflffl
SPECIAL PRICES ON
ASSEMBLED ATOMS
8k -2k. . .£135.00
12k-12k . . .£21 0.00
SEKOSHA
GP100. . .£199.00
WHILE STOCKS LAST!
PLEASE ADD VAT @ 1 5% TO ALL PRICES
SECURICOR DELIVERY £4.50
10% OFF ALL OTHER
ACORN PRODUCTS
To: Anglia Computer Centre, 88 St. Benedicts Street,
Norwich NR2 4AB Tel: (0603) 29652
I enclose cheque for £
Please debit
my Access No
Signature.
Name
Address
Telephone
ACORN USER SEPTEMBER
PCW Show . . . September 9-12 .
. Barbican . . . London
Acorn are exhibiting on two
stands at the PCW Show in
London's Barbican Centre on
September 9-1 2.
Stand 200 is for hobbyists in
the upper hall A and features a
host of computers for keenies to
play with. An Econet will be on
display with the new System 5s
as file servers. If you've never
heard of Smartarm, now's your
chance - they're robotic arms
produced by Systems Control
Ltd and worked by Atoms.
And if you want to see a laser,
Acorn have Laserpoint - where
the beam is controlled by an
Atom.
The lower hall B holds
Acorn's exhibit for educational
and business users on stands
317 and 322. Dedicated BBC
machines will demonstrate word
processing, ULA chip design
and circuit board drawing.
Again you will be able to get
your hands on the keyboards to
test out software for schools and
the office.
An interesting application on
view is a spectrometer used to
diagnose certain cancers, with
the help of Acorn micros.
The upper and lower stands
will never be far away - they're
connected by Econet.
And last - but certainly not
least - there's the Acorn Arcade
in hall A on stands 221, 223,
225, 227, 229 and 331. There
will be applications galore - all
using Atoms and Beebs.
The staff of Acorn User will be
on stand 444 in upper hall B
under the wing of Addison
Wesley Computing, the publishers.
Also featured will be books and
software for schools and colleges.
EXTRAS IN THE ARCADE
Computer Concepts specialise
in software for the BBC micros
(we deal with no other machine)
and will be demonstrating the
Wordwise word processor. This
ROM-based text editor and
formatter written specifically for
this computer is a sophisticated
piece of software.
We will also have a large
range of cassette-based software
on sale including games such
as Snake, Fruit Machine, Cube,
etc., and utility programs as well
as Basic Logo.
Electronequip specialise in
software and services for Acorn
products. A full repair service
(including warranty) is available,
as well as support for customer
modifications. For details phone
(0705)325354.
Eltec Services of Bradford are
dealers for Acorn products,
including the BBC micro and the
ACT Sirius 1. See Eltec Services
in the Acorn Arcade at the PCW
show and receive extra help and
attention and see some exciting
products. Or contact them on
Bradford (0274 491372).
Silversoft will be demonstrating
and selling their range of
cassette-based BBC micro-
computer software. Prices range
from £5.95 and all the cassettes
come with detailed instructions.
Microage Electronics will be
demonstrating and selling a
complete range of Atom and
BBC compatible disc drives,
printers, cassette recorders,
monitors, paper and software.
Microage from London are
promising some bargains on
their two stands.
Mutek on stand A8 will have for
sale: Voxbox (speech synthesiser);
Spriinter (see GB Computers on
stand A11) and will be
demonstrating their range of
add-ons for the BBC - and other
micros. Details from Mutek (MSF)
Ltd., Tel: (0225) 743289.
GB Computer Products will be
on stand A1 1 showing how
Mutek's Spriinter stores print
data in its own memory, thus
freeing the computer for other
tasks. The machine will be on
sale. Details from GB Computer
Products, 14 Greenwood Grove.
Winnersh, Wokingham RG1 1
51 H. Tel: (0734) 786635/791 678.
8
ACORN USER SEPTEMBER
(3(3(3 Microcomputer
BBC Model A £299
Model B £399 (Inc. VAT)
(Carr. £8/unit)
Model A to Model B Upgrade Kit £60
Memory Pack 8X84816AP £21.60
Print & User Parts Kit £9.50
Analogue Kit £7.30
F.D. Part Kit £70
RS423 & VDU Parts Kit £10.80
BUS & Tube Parts Kit £7.50
(the above prices do not include fitting charges)
All mating connectors with cables available in stock
Full range of ACORNSOFT, BUGBYTE & PROGRAM POWER software always in stock
PHONE/SEND FOR OUR BBC LEAFLET
ACORN ATOM
Atom Kit £120, Basic Built £135
Expanded 12K + 12K£175 8K + 5K + Colour Card £169
(Carr £3/unit)
Atom Upgrade to BBC £45 F.RROMC19 IK RAM £1.80
Work ftjck ROM £26 Tool Box Rom £25
All ATOM Buffers & Connectors in stock
Atom Forth £10 Atom Lisp£15 Atom Calc £34
Monitor ROM for direct entry of Machine Code £16
Atom Disc fc*ck£299 + £7 Carr.
PHONE/SEND FOR OUR ATOM LIST FOR FULL DETAILS
HUNTERS
NEC PC8023 BEC
*80 Cols. 100CPS
*B-directional Logic Seeking
'Proportional Spacing
"Forward & Reverse Line Feed
*H-Res & Block Graphics
'International & Greek
Alphabet
*Auto underline. Super & Sub Scripts
EPSON MX80C100F/nn
*MX80: 80 COLS. 80 CPS
•MX100: 136 COLS. 100CPS
*Bit Image Frinting
"Bi-directional Logic
Seeking
'International
Characters
*32 print FOmS
*Auto underline.
Super & Sub Scripts
Our new low price £340 + £10 Carr. MX80FyT3 £330. + £8 Carr
Printer Cable £13.50 1000 sheets 9W x 1 1" paper £14.00+ £4 Carr.
500 sheets 9W x 11" paper £4.50 + £2 Carr MX100FA3 £430 + £10 Carr
SEIKOSHA GP100A
'80 COLS. 30 CPS
•Self Testing
only £1752« £6 carr
Hi-Res Graphics
Variety of interfaces, spare ribbons available from stock
MONITORS
BM1401 Colour monitor BM12EA Green Screen Monitor
RGB Input/Separate Video Sync. 18MHz Scan Frequency
400 dots at Centre #40 x 25 char Anti ^are screen
5x7 dot format • 7 Colours
15 MHz Scan Frequency
£240 + £8Carr
80x24 char
£99 4- £6 Carr
Computer Grade Sarys
Cassette Recorder £24.50
Recorder head £3.50
(specify type required)
Computer Cassettes 50p ea.
or £4.50 for 10
Floppy Disc Drives
FD50A in Cabinet with PSU £190 + £6 Carr Dual Disc Drive Connecting Lead 36" long £14.00
2 x FD50A in Cabinet with PSU £360 + £10 Carr BBC Single Drive £204 + £3 Carr
These drives are fully compatible with BBC Mao BBC Dual Drive £338 + £6 Carr
Singie Disc Drive Connecting Leads 36" long £9.00 PRINTERS, MONITORS & F.D. Drives Carry 12 months warranty
The above are just a few of the items from our large stock range. We carry a very wide range of
connectors, made up cable assemblies, TTLs, CMDs, Microprocessors, Interface & Linear Devices, RAMs,
EPROMs, CRYSTALS etc. Our price lists, catalogues, leaflets are available on request. Our large stocks enable
us effect same day despatch on most orders.
Orders from schools, colleges and educational establishments are welcome.
All prices include carriage and VAT
Please add 40p for P&P/Carr. unless stated otherwise and VAT at 15% to the order value.
MAIL ORDERS TO: 17 BURNLEY ROAD, LONDON NW10 3ED
Tel. 01-452 1500/450 6597 Telex 922800
RETAIL SHOPS: 15 BURNLEY ROAD LONDON NW10 395 EDGWARE ROAD.LONDON W2
ACORN USER SEPTEMBER
BBC PLANS
AUNTIE
PI'
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CHRS<14i>
Thu 29 .Jul ll :34^i*
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DATE 18 ";Data
This is an axampla of a simpla
program for tha BBC Microcomputer
is intended that it is loaded diractlc
into a computtr fittad with a talatax
adaptor, which is whg it is difficult
to raad Anothar varsion of tha sama
program follows which can ba copiad
down bg a programmar or raad bg tha
machma .
This mathod of distributing computer
Programs is call ad TELE ]
flnotntr Ex«n
by DAVID
ALLEN
Thu Z9 Jul 11 33'4?
io :-s ?r:*t
io rS«CHRS-:i30J*CHR$Ci4i)
30 T$»"THE ^ODIPIED ->ULISN DAT£"
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"AR*» 19" v
feo INPUT 'ENTER THE MONTH (1 to 12^"
70 INPUT 'ENTER th£ DAY IN t H £ MON^-
'0 3l>*>" PRINT
80 IP "'■I OR M=*2 ThE^ L-l Ei-SE L»0
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30 6C0:*<M+i*< I2*w) > >
100 s 9'nt -THE MODIFIED JULIAN DATE IS
-Dare
.«IH^eC TO.EBOFTWARC iA IO REM LANDER
'? a lunar landar ftamalL ii REH CO bb
1982IL 12 REM bg Jim MurraylL 13
rem Vara ion 1.1 / Harch 1962IL 14 REM
rSrd* 32K BBC HicrocomputariL 20 ON ER
MR REPORT : GOTO 320ML30 MODE 7HL SO
W^ntrolL 60 MODE SIL 70 VOU 23,2
40,B,B,28,28,62,62,62,62;L BO VOU 23,2
41,62,62,62,62,62,62,62,62£L 90 VOU 23
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DU 23, 243, 28, 60. 30, 60, 126, 10^162, l62iL
110 VOU 23;B202;0;0;0;IL 120 VOU 19,2,
2,0,0,0IL 130 VOU 28,0, 19, 11, 1U. 140 9
H-t000906HL 150 *FX 11 1IL 160 PROClab
alsllL 170 PROCmoonllL 180 PROCinit lal is
• HL 190 VOU 5»L 200 XX-960HL 210 CCOL
0,3HL 220 REPEATIL 230 burnt- INKEYS<0
>HL 240 *FX 15 1HL 250 IF burnt-"" THE
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30 »L 260 PROCcalCulataHL 270 PROCdai
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Ixampla of a simpla
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THEHZ
Shape of things to
come. . . these three
pictures are all taken
from the Ceefax
service, showing just
what the BBC is up to
A
,n exciting new use for the
broadcasting television signal is
the transmission of programs on
Ceefax which can be received by a
decoder and immediately 'run' at
home on a BBC micro.
Telesoftware could provide broad-
casters with the chance to provide
viewers with interactive material to
back up a television series.
A computer program - if it works
and satisfies editorial and technical
criteria - can be run into the Ceefax
computer at Television Centre to
appear as a series of cycling sub-
pages on an allocated page of the
Ceefax magazine. You can see an
example of telesoftware on pages
703 and 704 of BBC1 Ceefax.
Hence, a computer program can be
broadcast to the user at home
instead of having to be typed in by
him or run in from tape.
A domestic decoder has been
developed by Acorn Computers,
working with BBC design and
research departments. If this
decoder is connected to the
television aerial and to the BBC
micro then, if the television signal is
good, it can detect the page of
Ceefax carrying telesoftware and
download it into the computer's
memory. It is exactly as if the owner
had typed it in on the computer's
keyboard himself.
B
ecause of the relatively high cost
of producing programs, telesoftware
would (initially at any rate), be likely
to come from public sources -
such as Department of Education's
Microelectronics Education Pro-
gramme, which is commissioning
software for use in schools.
Alternatively, some material might
consist of modified programs
designed to encourage subsequent
sales.
Given sufficient resources, there
are many possibilities, ranging from
'game of the week' and quizzes to
the transmission of political or
economic data to be processed by
home computers.
Finally, there is the idea of a club
page, where viewers' programs can
be put on the air. Editorial
10
ACORN USER SEPTEMBER
PLANS
PI 98 CEEFAX 198 Thu 29 Jul
1 1 56/ is
1'9
SOFTUARE
NEUS
NUMBER Z
UiELCOME to the second edition of REM -
interested in microcomputing/
particularly those who have or are
getting a BBC Micro.
The newsletter will be updated every
■fortnight at first, and will include
lilMiuflf!
peripherals as they become available
For newcomers, the explanation of
telesoftware and the address for
information about the BBC Micro are
b»ing repeated.
Telesoftware is on the way,
and judging by these pictures
coming over the airwaves from
the Ceefax stable, Auntie is
pretty near to sorting things
out at her end. Present trans-
missions - like the Channel 4
testcards - are only experi-
mental, with engineers down-
loading programs to test
Acorn-built telesoftware re-
ceivers. Anyone with a Ceefax
set can pick up these pictures,
but the receivers to download
software directly into BBC
micros are not yet available.
The REM newsletter page is
coming over Ceefax to let
people know just what is
happening and provide some
simple programs. We hear
that there will be programs to
interest every sort of user -
games, educational, business
and household. The programs
are in BASIC but have special
symbols which are decoded
by the BBC teletext unit (see
the letter on page 60).
responsibility for telesoftware will
lie with the editor of Ceefax.
Test transmissions are already
on the air and decoders should
soon be available. They will not
require the use of teletext television
set and, indeed, will enable those
who own model B micros to receive
standard teletext transmissions
from the IBA and BBC as well as
telesoftware. The only thing which
may not be possible is the mixed
picture and text facility used to give
subtitles for the deaf. However, the
decoder will enable certain other
features of teletext to be used, such
as the storage of 'linked' pages.
This will mean that the viewer will
not have to wait for these pages to
cycle round - they will have been
captured automatically by the
computer's memory
Telesoftware is the first chance
to provide interactive material as
part of the television signal. It is too
early to tell how the service will
proceed, but interest has been
considerable. *
David Allen is producer of the
Computer Programme and editor
of the Computer Literacy Project
Guide in
a nutshell
The revised User Guide contains
many tips on good programming
scattered throughout so here, I
have gathered a few together.
Use as few GOTOs (and, in
general, GOSUBs) as possible,
instead, use procedures and
functions at the end of the program.
Try to declare LOCAL variables in
procedures. Never define procedures
and functions within the body of a
program. But GOTOs are useful for
handling errors. When developing
programs, redefine one of the
function keys to give mode 7 and
then LIST.
Don't waste precious time trying
to memorise VDU codes and *FX.
Remember, the VDU statement is
generally preferable when sending
characters to the screen.
CALL transfers control to a
machine code subroutine. Use it
within a Basic program only if you
have a thorough grasp of assembly
language, otherwise you may mess
up your program. The CHAIN
statements come in handy if you
are writing a game with a lot of
instructions.
The 'resident integer variables'
@% and A% to Z% help you retain
values that would otherwise
disappear after CLEAR, NEW and
LOAD.
When using the INPUT
statement, print a message on the
screen to tell the user what
response is expected. A good way
of suppressing the ? mark is by
having "" just before the input (X, or
whatever) you expect from the user.
Use the ESCAPE key for stopping a
program; avoid using BREAK.
It is bad practice to jump out of
a REPEAT -UNTIL loop with a
GOTO statement. If you do jump
out, jump back in. Always exit a
subroutine with a RETURN. Avoid
leaving it with a GOTO.
These are just a few points, and
the best exercise you can do is to
make notes of all the advice you
come across. £
Meyer Solomon
Software Editor
BBC Publications
ACORN USER SEPTEMBER
11
ED OB ELTEC SERVICES LTD
BBC Microcomputers
BBC Model "A" (In Slock Now!) £326.00
BBC Model "B" (In Stock Now!) £435.00
BBC Model '■A" plus exlra 16K memory £367.86
16K HITACHI memory (as fitted by ACORN) £41 .86
FULLUPGRADEKIT(GenumeACORN issue) £100.00
UPGRADE KIT Fitting Charge
£10.00
14" Full colour Monitor lUsed in BBC
£309.35
Computer programmes)
12" Green Screen MONITOR
£126.00
RGB Monitor Lead
£5.00
Monitor Lead
£5.00
GP100A Printer
£247.25
Printer Cable
£18.40
Cassette Recorder
£26.00
Cassette Lead (7 pin DIN/3 Jacks)
£5.00
Software
Sinclair(IJK) Software Cassettes 1-7
from £3.95
Bug Byte Golf (B)
£7.00
Bug Byte Multifile
£25.00
Bug Byte Spacewarp (B)
£11.50
Bug Byte Polaris (B)
£8.00
Bug Byte Backgammon
£8.00
FULL RANGE of ACORNSOFT BBC
all £9.95
CASSbl IES
NEC30hr Basic
£5.50
Practical Programmes for the BBC
£5.95
Computer Johnson-Davies
Basic Programming on the BBC Computer
Cryer
£5.95
COM
PUTER
£2.50
£23.00
£343.00
£11.75
£30.00
£32.50
PS Come and see us in the ACORN ARCADE at th
We'll have lots of exc
Atom Microcomputer
Expand Your Atoms Capability
Extra Memory (21 1 4L) per K
Floating point ROM
ACORN 96K Disk Pack
Disk Buffer Pack
Word Pack ROM
Very Special
DISATOM SUPER ROM - undoubtedly the
most advanced chip of its kind on the market!
1 7 BASIC words are made available, including
the most powerful READ. DATAand RESTORE
you will ever have seen.
5 MACHINE LEVEL Functions including
TRACE and M/C DEVELOP which make the
ATOM absolutely TRANSPARENT!
This is a chip which no serious ATOM user
can afford to be without. Complete with
manual
Utility ROM Switch
Up to 4 ROMs keyboard selected £41 .79
Prices are VAT exclusive. P&P 50p Books, cassettes chips.
Atom Magic Book £5.50
Getting Acquainted with your ACORN ATOM £7.95
ATOM FORTH Cassette £1 1 .95
ATOM FORTH Manual £6.00
Hardware items £3.00 delivery by Securicor
ELTEC SERVICES LTD
231 Manningham Lane
Bradford BD8 7HH
Tel (0274) 491372
e PCW show Barbican Centre London Sept 9-1 2;
iting offers & products.
ACORN ATOM 8K + 2K E129
ACORN ATOM 12K + 12K £179
ATOMCOLOUR BOARD £39
FLOATING POINT ROM £22
BBC ROM PACK EPhone
POWERSUPPLY 1.8A £10
IT'S HERE AT LAST!
SEIK0SHAGP-100A
000MICRD
• DOT MATRIX PRINTER
• 80 CHARACTERS PER LINE
• 30 CHARS/SEC
• FREE HI-RESOLUTION 'DUMP OUT' LISTING
— ACORN Printer Cable £16 + VAT
£1 " VAi taEfi ATOM Modification EXTRA
000 MICRO
EPSON MX80 F/T2 - The printer recommended tor the
BBC Microcomputer.
• Dot Matrix Printer • Hi-Resolution Graphics
* 80 Cps * Bi-directional Printing
RAM KITS: Upgrades the Model ft to 32K RAM
Supplied with tull titling instructions £29.90 + VAT
ANALOGUE KITS: Suitable tor adding joysticks.
controllers etc £15.00 + VAT
POWER INTERFACE & I/O PORT: Enables a
Centronic Interface printer to be attached . . . £16.00 + VAT
MODEL 'A' TO MODEL 'B' UPGRADE
£86.00 + VAT
DISC EXPANSION Phone
DISC DRIVES Phone
COLOUR MONITORS £249.00 + VAT
Send for details on other items, cables, cassettes, plugs,
software etc.
Why not send your machine to us for upgrading?
12
ACORN USER SEPTEMBER
BUSINESS
The BBC micro is too new for
many uses, but it has potential
says John Turnbull
T
he BBC micro for business
computing - is it on? This is the
question asked by many who have
ordered a system and by many
others who are wondering whether
to take the plunge.
What must be made clear
straight away is that the present
system is not suitable for serious
business applications - as indeed
is the case with any cassette-
backed system lacking application
programs. Any business user who
identifies a need for a computer will
require disc drives, printer and
suitable programs.
But that's not the end of the
story, as many purchasers of
systems are exploring computing in
anticipation of viable systems. For
some this will mean rejecting the
BBC system in favour of others
which offer specific application
packages. But for others, the
growth of facilities will be more
than adequate and, assuming
programs emerge, their organisa-
tions will build around this flexible
system.
F
irst though, you've got a machine
and, assuming you can get near it,
let's see if it can be used now to
help the business. > / ^^H
For a start, here's a program
which does no more than add up
numbers - like a calculator but
without the frustration.lt simply uses
the fact that the computer display
contains much more information
than a calculator display.
10 PRINT "Enter numbers to be
added"
20 PRINT'To finish, enter a zero"
30 T =
40 REPEAT
50 INPUT X
60 T = T + X
70 UNTIL X=0
80 PRINTT
Now that's a bit crude and you
don't need to know much about
programming to improve on it. One
less obvious technique would be to
suppress the line feed after INPUT
and thus provide much more
information on the screen. To do
this, control the INPUT with a TAB
function. Omitting the
instructions, the above
could
become:
original
program
R = 6
30 CLS: T=O:P=0
40 REPEAT
45 C = 10 * (P MOD 4)
INT(P/4)
50 INPUT TAB(C.R) X
60 T = T + X:P=P-M
70 UNTILX = ■
80 PRINT: PRINT "total" T
(Note: the INPUT position is defined
by row R and column C)
Even this little program can reduce
significantly the time spent
preparing VAT returns. Another
program aids stock valuation where
stock had been purchased (and
prices quoted) in varying quantities.
Fundamental stages in the program
were:
INPUT "NUMBER IN STOCK" N
INPUT "PURCHASING QUANTITY"
Q
INPUT "COST PER QUANTITY" C
TOTAL = TOTAL + N * C/Q
The opportunity to develop and use
simple models such as these will
grow considerably as financial
modelling packages appear.
First priority will be twin floppy
disc drives. As with any system, two
drives are suggested to provide
security copies. For the new user of
computers it is essential to retain
back-up copies of essential files
and institute a system of archiving.
An alternative to floppy disc
storage is the Winchester disc
which is attractive in terms of
speed, reliability and capacity.
For applications in which the
output stays in house, a cheap dot
matrix printer will suffice. However,
if documents are to be sent out a
letter quality printer is essential.
As
for software the small business
may require packages specific to
the trade or may be looking at
standard applications. Production
of such packages takes time, but
one interesting feature of the BBC
system which may overcome this is
the Tube architecture. fl^^ft
The Tube enables the heart of
the machine - a 6502 processor -
to be relegated to input/output
processing and the main
processing to be undertaken by a
second processor. Early plans are
for the second processor to be a
Z80 microprocessor and, with this,
the way is open to adopt the
ubiquitous CP/M operating systei
This has many critics, but its
availability brings in its wake a.
wealth of existing application
software. An efficient CP/M option
may be the determining factor for
many would-be purchasers of the
BBC micro. *
John Turnbull is manager of
microsystems administralion at the
National Computing Centre, which co-
ordinates the Federation of Microsystems
Centres. These centres, supported by
Department of Industry, offer an impartial
service of workshops, advice and
training on business systems. Further
details from: the Microsystems
administration unit, National Computing
Centre Limited. Oxford Road. Manchester.
M1 7ED
ACORN USER SEPTEMBER
13
BUSINESS
John Gordon sets up mailing lists
and simple files on the BBC micro
F
or the first time user the BBC
machine offers a very friendly
introduction to computers - and
can do some real work. A first task
could be to set up a mailing list
which involves: creating a file of
names and addresses on tape;
reading this information and writing
it to the printer.
Using the BBC micro we create
the mailing list as follows:
• Instruct the computer to open
(for output) a file on the cassette
tape. This gives the computer
advance warning that you wish
to write information onto tape.
When a file has been opened,
the computer gives it a channel
number, and writes the file name
onto tape. The BBC BASIC
command for this is:
180 ch_no=QPENQUTi"ma. ■ _: ist")
from now on the channel number
ch_no is used to refer to the file.
• Once the file is opened, we can
accept names and addresses
from the keyboard and write
them to the tape. We repeat this
process until the last name,
which is a special, recognisable
name - endofjist, perhaps.
This would be coded as,
200
REPEAT
210
INPUT name*. address_l*.
address* 2*. address_3*i p_code$
220
PRlNTttch— no* name*,
addross.lt- address ' 2*>
address_3*> Q_code*
230
UNTIL name*="end_of_i ist"
Notice line 220, PRINT#ch_no
writes the following data onto the
tape. Lines 200 to 230 are
continually repeated until the
special name endofjist is
entered. Thus we can end up
with a fairly extensive set of data
on tape.
At this point in the program, the
computer does not know if all
the data has been finished.
Therefore the programmer must
instruct the machine to close the
file. Thus:
>300 CLQSE*tch_no
If we collect these three sections of
code together we would have a
program which could be used to
create a mailing list on tape. As it
stands, the program would not look
very good - it would not be user
friendly. The following program
expands on the code to make it
more usable. Notice the use of
REM statements to make it self
documenting.
100
PEC" Pail ms hst J.Gordon.
120
REM for the BBC micro
130
ch_no=OPENOUT<:"'!ia* ■ _i ist")
140
150
REPEAT
CLS :REM clear screen
1E0
PRINT "Enter name and address.
170
use name=end_ of _ 1 ist to finish"
INPUT '"Name - "name*
180
190
INPUT ' "Address_l - "address.!*.
"Address_2 - "address_2s,
* "Address_3 - "address_3*
INPUT' "Post Code - "p.code*
200
PRINT#ct-»_no» name*, add ress_l*?
210
220
address_2s» address_3*. p_code*
UN T IL name*="end„of _l ist"
CL0SE#ch_no
230
END
When this program is run, the
following appears on the screen:
>RUN
RECORD then RETURN
Enter name ana address?
use name=end_of _ i ist
to finish
Name - Jim Smith
Pddress_l - 3 The Close
0ddress_2 - Paisley
flddress_3 - Renfrewshire
Post Code - PP1 2BE
Enter name and address?
use name=end_of _t ist
to f i n i sh
Name - end_of list— list
flddress_l -
Address_2 —
Address-? -
Post Code -
Thus we can make the program
appear straightforward.
We now have the problem of
getting the names and addresses
off of the tape and onto sticky
labels. The program in this case
takes the following form:
• open the file for input. This is a
similar instruction to open for
output. The BASIC statement is:
:B0 ch_no=QPENI(vi<"mai i_
st">
Read a name and address from
the tape and write it to printer.
With the BBC micro, we have a
very simple means of getting
data onto the printer. We issue
the command VDU 2, and all
subsequent data PRINTed, will
appear on both the screen and
the printer. If we wish to stop
printing we issue the command
VDU 3. We can then keep on
reading and writing names and
addresses until we get to the last
name (end-of-list). Thus:
200
REPEAT
210
INPUT#ch_no? name*?
address_l*> address_2*.
address_3S? p_codet
220
PRINT name*, address_l*.
address_2*. address_3*? P-COdef
230
UNTIL name*="end_of_l ist"
Notice in line 210, we are inputting
from the tape (channel = ch_no),
and PRINTing to the screen. If we
are using the printer, we add the
following two lines,
190
240
VDU2
VDU3
•
Lastly,
file.
as
before
we
close
the
300
CLOSE#ch_no
The above pieces of code would
enable the user to obtain a printout
of the mailing list, but it must be
fine-tuned to fit a sticky label. This
is done by printing lines onto the
label to get the names and
addresses lined up (see program 1).
When using a disc system, we do
not need to know the value of the
last name. The system is provided
with an end-of-file function - EOF#.
We can replace line 280 with:
* ~>
280 UNTIL EOF*tch-no
14
ACORN USER SEPTEMBER
o
BUSINESS
J.
Program 1. This was used to set up
the sticky labels reproduced on the
right by a printer.
*e n
m
'Sf
Sn,
th
ey
• WSh i
OS.
2BE
re
19B2
Key is pressed
100 REM Sticky label print program
110 REM J.Gordon. M. E. D. C. * Pa.siey.
120 REM Written for the BBC micro
130 CLS
160 PRINT"This program prints the mail ins
listonto sticky labels"
150 PRINT"Load and rewind the correct tape"
160 PRINT"Make sure that sticky labels are
in Printer and alisned"
170 PRINT"Press any key to continue"
180 A*=GET«:REM Program pauses unt.i
190 CLS
200 PRINV'Press PLOY on tape"
210 ch_no=OPENINC"mai i_i ist")
220 VDU2:REM Printer on
230 REPEAT
235 REM Lines 250 and 270 are used to Position printer
240 INPUTttch_noi names. address_l*. address_2*. address_3*. P_code*
250 FOR Ibi JO 3: PRINT" ":NEXT I
260 PRINT name*. * . address_l*. * . address_2*. * . address_3*. ' . P_code*
270 FOR 1=1 TO 3:PRINT" ":NEXT I
280 UNTIL name*="end_of_l ist"
290 VDU3:REM printer off
300 CLOSE#ch_no
310 END
j oh,
G,
Ne
a s
Sc
w
Ro
ott
sow
a,j
'*">e s
Th
* Ci
int
ffe
'SI
if
ey
*s<
*r, t
ftte
re w .
GGh
in,
•n«i_
Of
- /
st
Thus we can see that it is not too
difficult to use the tape operating
system to hold files of data, and
subsequently to retrieve that data. I
leave it as an exercise to the reader
to amend the second program to
print out a selective mailing list,
(use IF statements around about
line 240).
One second application shows
some of the limitations of a
computer with only one tape
cassette for data storage.
The simplest stock control
system consists of the stock file, a
file containing all transactions on
the stocks (all the withdrawals and
additions to stock) and a printout of
all items which need to be
recorded.
We would use the transaction file
to update the stock file, and the
updated stock file to produce a list
of all items recorded. Thus the
flowchart would be as in figure 1 .
This is only part of the full
/ Old
( SIOCK k
/ Transaction/
A f,le
Update
program
f
I
' New /
stock
Re -order
program
I
I
fleorfle'
RSI
FIG. 1
system, there would have to be
other programs to set up the
transaction file, and to ensure that it
was correct and in the correct
order. But even with this restricted
system we have problems. We see
that the stock-update program
requires the BBC micro to access
three files simultaneously - but we
only have one cassette unit. With
the machine, in its present form,
therefore, this type of program
cannot be implemented. Of course
with discs there would be no
problem
However, if the stock file is not too
large, then we could read the file
into memory in the form of an array
of data, then update this array from
transactions on tape, and lastly
dump the array back onto tape.
Figure 2 gives the system diagram.
In this amended system we only
need one tape at any one time.
Before we go any further, let us
consider what an array is. An array
Old
siock
file
Read into
memory
Array
Of
StOCk
file
Transactions f
Update
DTQQram
I
Wfite to
tape
Calculate i
pfint
reorders
New
s:ock
file
FIG. 2
is simply a table of data held within
the computer's memory. To hold an
array in memory, the computer must
be instructed to reserve space for
it. This is done by using the
DIMension statement. Thus:
lOBDIMnametf 10)
assigns space for 10 items of
information to be held in an array
name$. To refer to any individual
element in the array, we use:
:B0PRINTnam**<
prints the third value of the array
name$ onto the screen.
To print the full 10 values of
name$, we would code:
200 FOR 1 = 1 TO 10
210PRINTnam»*<n
220 NEXT I
with this additional feature, let us
construct a computerised system
for a stock file holding the
information: stock number; a
description of the article; the
number in stock; the minimum
allowable stock level and the
number of items to be recorded if
necessary. Thus:
Stock Descrip-
no tion
1 Widget
2 Pofor
3 Duferry
4 What for
5 Thingies
6 Eh
7 Jiffies
8 What-you-
call-ems
9 Bits
1 Pieces
No in
stock
Rec- Rec-
order order
level quan-
tity
10
7
11
23
13
8
18
8
13
8
5
6
4
10
5
2
10
2
5
3
5
10
6
12
4
4
20
3
4
9
ACORN USER SEPTEMBER
15
^^^HMM^H^HBMMI^MB^^M
BUSINESS
■■■M^HHBM^^^^^HM
i^^^^^hh
^^■^V^B^^P
■■^^■V^
The transaction file is a file
containing information regarding
withdrawals from and additions to
stocks. The format of the file is:
stock number, code, quantity.
Notice the stock description is
not held, only the stock number,
which reduces the size of the file.
The code is 1 for a withdrawal from
stock, and 2 is an addition. We will
assume that the data have been
verified. For example, there is no
stock number 11, say. The file
contains the following, information:
Stock Num
ber
Code
Quantity
3
1
6
5
1
3
2
2
9
3
2
4
8
1
1
7
2
3
3
1
-8
1
1
2
Program 2 can be used to update
the stock file. The following printout
was obtained using the given data.
Items to be reordered:
3Du-ferry 1 4 6
A dump of the new stock file gave:
lWi dset
8
5
5
2Pofor
16
6
10
3Duf er ry
1
4
6
4Whatfor
23
10
12
5Thi rig ■ es
10
5
4
6£h
8
2
4
7Ji ff ies
21
10
20
8What_you_ca I I
_ems 7
*1
r
3
SB its
13
5
4
10Pieces
8
3
9
If we do not have a disc unit
available, then the maximum file
size is limited by the memory
available. With a disc drive,
however, we can have fairly large
files for holding data. But there are
still limitations.
;00 REi"
oas-'d stocH-uPdite Program
110
120
130
REM J.Gordon. M. E. D. C. . Pa • s i ey . 19S2
160
150
160
170
REM Wntt*n for the BBC Micro
REM This program reads a transaction
<i '? to update a master stock file
trans=OPENlN< "transacts")
Old_StOCkS=QPENIN("stOCk_f . I e" )
n»w_stocKs=OPENOUT("riew_stocks")
INPUTSt rans. stkno. code, auant 1 1>
ISO REPEAT
190 INPUTftold-stocks. stock-number,
descr ■ Pt i on*, no-i n_stock. reord_ i evei .
reord.ouant
200 IF" stock_number=stkno THEN PROCuPdate
210 PRINT*new_stocks.stock_numb»r»
desCf i ot i on*i no_ j n_stock. rec>rd_ l eve l •
reord_ auant
220 UNTIL EOFl»oid_stocKs
230 CLOSE#trans
240 CL0SE*Old_StOCks
250 CLOSE»new_stocKs
260 END
2S0 DEF PROCuPdate
290 IF code=l THEN no_i n_stock=no_ » n_stock
*- auant. ty ELSE no_«n_stc-ck=no_ i n_
stock + Quantity
300 INPUTtttrans. stkno. code, auant ity
310 IF stkno =stock_number THEN PROCuPdate
320 ENDPROC
Program 2
The simplest means of holding a
file on disc is to arrange all stock
records to be held in sequence - a
sequential file.
If we wish to process information
held in a sequential file, then we
must search for the required
information starting at the
beginning of the file and read
records one at a time until the
search is successful. In the last
example, where the stock file was
in memory, we did not have to use
this approach. We were able to
process the transactions without
considering stock number sequence.
When using a sequential file on
disc, we would normally sort the
transaction file into stock number
sequence thus:
Stock Number
Code
Quantity
1
1
2
2
2
9
3
1
6
3
-2
4
3
1
8
5
1
3
7
2
3
. 8
1
1
We can take advantage of the order
of the transaction file when we
update the stock file. It is possible
to update the stock file in one pass.
Notice that stock item 3 has three
transactions made against it. We
have to take this point into
consideration when we attempt to
update the file.
The transaction file must be read
independently of the stock file to
handle multiple transactions on the
same stock item. Program 3 will
carry out this task. Notice the use
of a recursive procedure to handle
the problem of multiple transactions.
One of the most common
requirements of a computer, system
is to retrieve information instantly.
This would not normally be done
using sequential files, as such
processing would be rather slow,
so we use random files.
Instead of reading the records in
the form 1st, 2nd, 3rd, 4th .. . we
could read them 4th, 17th, 2nd, 9th,
1st, 17th... with the possibility of
reading a record more than once.
The programing involved is fairly
complicated and will be considered
in a later issue. 9
John Gordon is a lecturer at the
Microelectronics Educational
Development Centre in Paisley,
Scotland.
100REM
110REM
120REM
1 30 REM
1&0REM
Stock Control System
J. Gordon. M. E. D. C. • Pa i si ey. 1982
Written for the BBC micro
This orosram is written
as a series of modules
150REM The first section sets up
the stock file
file is he i d in
the form of 2 arrays,
being a string array
to hold the descriptions
170REM The other >s a 2 dimensional
array containing the numeric
data of the stock file
1S0DIM descr i pt i on** 101 . numbers': 13. 4}
space for
The stock
memory in
the -f i rst
n the stock f i le
190REM We now read
200CLS
210PRINT "Load stock file tape into
cassette and rewind"
220PRINT "Press any key when ready"
230a*=GET*
240PRINT "Press PLAY on recorder"
250stocks=OPENIN("stock_f i I*" >
260FOR 1=1 TO 10
270 INPUT*tstocks» numbers* I. 1).
descr i pt iont(l)i numbers * I. 2>.
numbers*! I. 3) .numbers ''I. 4>
2S0NEXT I
290CLOSE*stocks
300 CLS
310PRINT "The stock-file in memory"
320PRINT"Remove Stock file and load
transact i on file.
rewind if necessary"
330PRINT"Hit any key when ready"
340a*=GET*
350PRINT"Updat ins Stock-file"
360trans=OPENINC"transf i le">
370REM The foilow.ns section of
code updates the- stock
file in memory
380REPEPT
390INPUT*ttrans. I. code, auant i ty
400 IF code=l THEN numbers* I» 2)
=numbers< I» 2)-auant i ty ELSE
numbers <: I. 2) =n umbers* 1 . 2)+auantity
410UNTIL EOFtttran-
420REM Stock-file updated
430CLQSE#trans
440REM The following section of
code prints ail items to be
reordered, and writes the new
version of the stockfile to taoe
450CLS
4G0PRINT"Load fresh tape into
recorder and rewind"
470PRXNT"Ensure that printer
is set up properly"
480PRINT"Hit any key when ready"
490a*=GET*
500CLS
510PRlNT"Process.ns ■
520VDU 2:REM start Printer
530PRINT" Items to be reordered!"
540new_stock=OPENOUT*"stock_f i le" >
550FOR 1=1 TO 10
560PRINT#new_stoc«Tnumbers(I. 1).
descr i Pt i on** I ) . numbers* I» 2) »
-numbers* 1 . 3 )t numbers* 1.4)
570IF numbers* Ii 2) <numbers* I. 3)
THEN PRINT numbers* I . 1) ,
descr i Pt i on** I ) i numbers* I-» 2) .
numbers* I. 3). numbers* I. 4)
5S0NEXT I
590VDU 3: REM stop orintout
S00CLOSE#new_stock
610CLS
G20PRINT "Job finished"
630END
Program 3.
Ensures independent
transaction file
16
ACORN USER SEPTEMBER
Wordwise
The most sophisticated piece of software yet written for the
BBC Micro. This full feature word processor is ROM based so
once fitted inside the machine (no soldering it enables the user to
gain INSTANT access to a powerful word processing system.
WORDWISE consists of two distinct sections - a text editor
and a text processor. The editor allows text to be entered at the
keyboard in much the same way as a typewriter except that the
carriage return is quite automatic. When editing the cursor can
be moved to any part of the document where changes can be
made either by overwriting existing text or by inserting new text
at the cursor position. In addition to the delete key, which works
in the normal manner, there are a variety of other deleting
options allowing characters, words, sentences or any specified
section of text to be deleted.
While editing or entering text, special instructions can be
embedded into the document. These embedded instructions are
interpreted by the text processor and control the exact layout of
the printed output. Some of the simpler instructions control the
positions of the margins, the number of lines per page or the line
spacing, etc.
There is not room here to begin to describe the many more
powerful features such as the block move and copy, search and
replace, the word counting facilities or the file handling
commands.
As an alternative to word processing this software can be
used to edit BASIC programs or any ASCII text. This enables the
programmer to use the vastly superior editing facilities of
WORDWISE on programs, e.g. automatic string search and
optional replace, etc.
Although this software is ideal for secretaries, authors or
journalists it will prove invaluable to anyone who has to prepare
letters, articles, leaflets or documents of any kind.
It is our aim to sell high quality software that, like the BBC
Micro, is excellent value for money. We believe that
WORDWISE compares favourably with other word processors
costing four or five times as much.
WORDWISE costs £65.00 + £1.50 p&p + VAT. Technical
details and an order form are available from the address below.
MEMORY KITS Model A Now only £26.00 + VAT
These kits upgrade the Model A to 32K RAM, the same as the
Model B, enabling it to run Model B programs and graphics.
Simple to fit - no soldering is required. Supplied with step by
step instructions.
SNAKE Model B £7.80+ VAT
This colourful arcade type game makes full use of the amazing
graphics (Mode 2) and sound facilities of the BBC Micro. One of
the best games around, fast moving and addictive - requires
quick reactions.
ADVENTURE 1 Model B £5.80 + VAT
An adventure based on the characters of the book 'Hitchhikers
Guide to the Galaxy'. Explore the 'Restaurant at the End of the
Universe'. 'Betelgeuse Spacedome\ read Vogon poetry, etc.
REVERSI Model A/B £7.80 + VAT
Play this classic board game, also known as Othello, against
your Micro. This game offers 3 levels of difficulty - level 3 is
extremely hard to beat.
CUBE Model B £7.80 + VAT
A simulation of the famous Rubik Cube. This program displays
a full colour 3 dimensional view of all sides of the cube. Choose
how jumbled you want the cube and then try to solve it. Stunning
3-D graphics.
FRUIT MACHINE Model A/K £5.80 + VAT
Another great game that shows off the superb graphics and
sound effects of the BBC machine. Features 'Nudge', 'Hold',
'Gamble' etc.
BASIC LOGO Model B £10.00 + VAT
The first implementation on the BBC Micro of the graphics
language LOGO. It graphically demonstrates the ideas of
defined procedures, sub-routines, loops, etc. This is an excellent
introduction to the LOGO language before Acorn release a
complete implementation in ROM in 1983.
SOUND IDEA Model B £5.80 + VAT
A utility program for those interested in the SOUND and
ENVELOPE facilities of the BBC machine. The first part of the
program displays all 18 parameters on the screen, any of these
can be changed by using the cursor keys and the new sound can
be heard. Pressing H (help) will give a full description of that
parameter. In the second part of the program the keys act like a
musical keyboard playing either the sound defined in the first
part or one of the 9 preset effects.
CHARACTERS Model A/B £5.80. + VAT
Forget about clumsy binary or hex notation when re-defining
character shapes. Just fill in the displayed grid with the required
shape and it will re-program the character and give the VDU 23
numbers for that shape. It can also save the character tables on
tape for use in other programs.
DISASSEMBLER Model A/B £5.80 + VAT
A machine code disassembler that runs on both models. Ideal for
discovering the workings of the MOS and BASIC. Invaluable
for the Assembly Language programmer.
CASH OR ROYALTIES
We offer a national marketing service for any quality software
for the BBC Micro. We pay cash, or for more substantial
programs a royalty. As for further details.
DMPUTER
Dept AC1
1 6 Wayside
Chipperfield
Herts. WD4 9JJ
Tel. (09277) 62955
ACORN USER SEPTEMBER
17
SAVE &&& - WHY PAY MORE
MATRIX PRINTERS
MX80 T Type in
MX80F/T
■typem
MX82 F/T
MX100
Type IE
Delivery free within 30m radius,
otherwise add £10 delivery charge per
order
BBC MICRO SOFTWARE
Quality Software designed by professionals
Utilities &8.00
An assortment of useful procedures
which can save you hours/days of
programming effort - date conversion,
input and validation routines, graphics
routines, sorts and many more.
Educational &7.00
Hours of fun and learning for children
Animated graphics will make your
children enjoy math, spelling, clock,
memory games etc.
Music Program &6.00
Lack musical ear? This amazing
program harmonizes (add chords to)
any music you type in.
GAMES
Super Life &8.00
Fast (machine code) version in a large
universe. Competitive Life - see the
reds and blues compete for space.
Killer Life - a new twist in this popular
game introducing predatory cells.
Cruncher A7.00
Super version of an increasingly more
popular game. Can the Cruncher crunch
through the crunchies in the maze
before the monsters get him?
Katakombs £8.00
Can you discover the secret in this
exciting Adventure type game?
Special Offer Any 3 cassettes for £16.50, additional cassettes £5.00 each.
Add 50p p/p per order.
All orders - add VAT 15% Cheque/P.O. TO GOLEM LTD, 77 Qualitas, Bracknell, Berks, RG12 4QC, teL (0344) 50720
WHAT PEOPLE ARE SAYING ABOUT OUR . . .
BBC MICRO GAMES
"... I bought all your tapes to date
for the BBC Micro and I think they
are just super, especially STAR TREK,
and the sound effects in CANDY
FLOSS really made me sit up! Well
done and keep them coming".
J. S . Paisley
"... I was very impressed, not only
with the cassette, but also at the
speed at which it came!"
— R.L., Cheshire
" . . . I must congratulate you on
your MUTANT INVASION cassette. I
have had it for two weeks now and it
is really superb. Incidentally, I have
beaten your high score of 4,500 —
mine is 7,580!"
— S.L., Berks
GAMES FOR MODELS A AND B
CASSETTE ONE
(i) STAR TREK. A superb version
with 8x8 Galaxy, Klingons, Pha-
sers. Torpedoes etc.
(ii) CANDY FLOSS. A tremendous
new game in which you run a
candy floss stall on Blackpool's
Golden Mile. But watch the
weather and the donkeys!
ONLY £5.95 inc.
CASSETTE TWO
Contains an exciting collection of
games with music and graphics to
keep the family amused for hours:
HANGMAN (in which you can
even enter your own category),
KRYPTOGRAM, DICE, BEETLE,
GRAND NATIONAL and MUSIC.
ONLY £3.95 Inc.
CASSETTE THREE
Contains, for the arcade fanatics.
— MUTANT INVADERS. A brilliant
new "Space Invaders" type game.
Can you destroy the mutants be-
fore they land and try to destroy
you with their radioactivity.
WARNING — VERY ADDICTIVE 1
ONLY £5.95 Inc.
CASSETTE FOUR
Contains BREAKOUT A terrific
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game. Practice your wall demoli-
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ONLY £395 Inc.
GAMES FOR MODEL B ONLY
CASSETTE FIVE
Contains BEEBMUNCH. Our version
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arcade game, and we believe one of
the best versions available. Stun-
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including multi-ghosts, tempting
fruits, super points, screams etc.
Liven up your micro with this tre-
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ONLY £5.95 inc.
CASSETTE SIX
Contains SUPER HANGMAN. The
special feature of this version is the
hi-resolution animated man. Watch
the expression on his face change
as the noose tightens around his
neck. Marvel at the detail of his
clothing — but don't take too long,
he grows very impatient! ! Contains
many categories from educational
to just plain fun! ONLY £3.95 inc.
CASSETTE SEVEN
Contains 3-D MAZE. Pit your wits
against the computer's logic in this
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computer sets up logical mazes (you
choose the size). And then it shows
the view you have of the maze in 3-
D each step you take as you battle
against the clock to escape! ! !
ONLY £3.95 inc.
ALL CASSETTES AVAILABLE NOW FROM: SINCLAIR (I. J. K. Software)
(All our software is available before we advertise) 55 Fitzroy Road, Bispham, Blackpool, Lanes
18
ACORN USER SEPTEMBER
REVIEW
that is
the question
Comparisons are odorous, said
the Immortal Bard, and so they are,
especially when the person making
them is biased. I'm sure you must
have seen advertisements for the
ZX Spectrum and noticed Clive
Sinclair's comments on the relative
merits of his and the BBC machine
- but I think we must allow that he
is a little biased! By the same
token, since I am writing in a
magazine called Acorn User, surely
I am likely to be biased - the other
way!
But I am not trying to sell either
machine, I am also a previous
owner of a ZX81, present owner of
a Spectrum, and have a BBC micro.
So I have had a chance to look at
both sides. I shall be referring to
the BBC model A, since that is the
ACORN USER SEPTEMBER
comparison originally made by Mr
Sinclair.
Should we in fact be comparing
these machines? The Spectrum
costs only £125 whereas the BBC
is £299. Well, maybe it isn't fair
comparison, but what Uncle Clive
started, others have continued. Tim
Hartnell in his review in Your
Computer said the specification of
the Spectrum exceeds that of the
BBC model A. As you make the
factual comparison of the two
machines, I think you will see this
is just not tenable. However,
although the Spectrum does not
come out as favourably as some
would like to think, you must
remember that it costs less than
half as much. Would you think it a
fair comparison to look at the
relative merits of a basic Mini
Metro at £3,300 and a Rover 2600
at around £8,000?
I have set out the comparison in
the form of three tables. The first is
an expansion of the Spectrum
advert, while the second and third
show features each has which are
not included as standard on the
other. I shall make no comment on
the facts at this stage - that is up to
you.
The Spectrum, as indicated in
Table 1 , is expandable on board to
48k RAM. and it has address, data
and control lines brought out on an
edge connector ready for all sorts
of peripherals. The ZX printers are
already available, and an RS232
79
REVIEW
TABLE 2 - Spectrum features
not standard on BBC model A
TABLE 1 - Comparison of features of the BBC model A
and the ZX Spectrum.
ZX Spectrum (16 k)
BBC micro, model A (1 6 k)
Price (inc. VAT)
£125
£299
Maximum RAM
48k
32k
(96k with second processor)
Standard ROM
16k
32k
Maximum ROM
16k
80k on board
256k on cartridges
High resolution
256 x 192 in 8 colours
graphics
^j i
(7k RAM)
320x256 in 2 cols {10k RAM)
or 1 60 x 256 in 4 cols (1 0k RAM)
or 80 x 96 in 8 cols ( 1k RAM)
{ie teletext mode)
RAM reserved for
approx Vfek
3V4k
operating system
{includes 26 integer variables)
RAM left in high
16-7- % = 8Vfek
16-10-374 = 2 3 /4k
resolution mode
for programs and
variables
maximum program
8 1 Ak
16-1 -3 1 /- = 11 3 /4k
and variable RAM
(teletext)
in any mode
Text
32 x24 (8 cols)
40 x32 (2 cols)
or 20 x32 (4 cols)
or 40 x25 (2 cols)
or 40 x25 (8 cols)
Programmable
21
32-224
characters
Processor
Z80A{3.5 MHz)
6502A(2 MHz)
Speed of Basic
Speed factor
Benchmark 1
4.9
1.0 4.9 x
Benchmark 2
9.0
3.1 2.9 x
Benchmark 3
21.9
8.2 2.7 x
Benchmark 4
20.7
8.7 2.4 x
Benchmark 5
25.2
9.1 2.8 x
Benchmark 6
62.8
13.9 4.5 x
Benchmark 7
89.9
21.4 4.2 x
Benchmark 8
25.1
5.1 4.9 x
Sound
single channel,
3 channels of tones + 1 noise,
frequency + duration
volume, frequency + duration,
full enveloping (14 parameters)
Cassette
1500 baud + VERIFY
1200 baud or 300 baud
interface
(verification possible using
*CAT command)
+ automatic meter control
+ MERGE
*EXEC can be used for
similar effect
Keyboard
40 calculator-type keys
73 full depression keys
on a steel base plate
BRIGHT
CIRCLE
BIN - direct entry of
binary numbers
PAUSE - an easy-to-use 'wait'
statement
CONTINUE - sadly lacking on
the BBC micro
copyright symbol ©
single key entry of keywords
TABLE 3 - BBC features not
available on the Spectrum
Assembler, called from within
Basic, full parameter passing
Graphics and text windowing
Procedures - fully recursive - local
variables- parameter passing
Direct entry and output
in hexadecimal
Real-time clock (Spectrum clock
has to be accessed by PEEKs.
POKEs and arithmetic calculations.
Structuring facilities within Basic in
addition to procedures:
IFTHEN ELSE
REPEAT UNTIL
ON GOTO
ON GOSUB
Word and string indirection (4 byte
and string PEEKs and POKEs).
1 6 user-definable keys (yes, 1 6 - in
O.S. 1.00 includes cursor keys
and copy key.
Other useful features:
AUTO RENUMBER DELETE
CHAIN *LOAD *SAVE *RUN
•SPOOL *EXEC *ROM TRACE
COUNT
Integer variables
ON ERROR GOTO, REPORT, ERR
and ERL for comprehensive error
handling
Multi-line function definitions
Facilities for logic and hexadecimal
manipulation: (AND) (OR) (NOT)
(not available as bit-wise operator
on Spectrum). EOR MOD DIV
TRUE FALSE
Extra string handling facilities:
INSTRING
STRINGS
SPC
Comprehensive file handling
facilities:
OPENIN
OPENOUT
PRINT*
INPUT*
PTR*
EOF*
CLOSE*
BPUT*
BGET*
EXT*
20
ACORN USER SEPTEMBER
REVIEW
serial interface is promised - but
surely the most exciting single
feature is the £50 microdrives, each
of which will give 100k of on-line
storage - and they are apparently
going to be stackable. Then there
will be interfacing units to enable
you to run your micro-mice or
model railways etc, and also
speech synthesis units. Already, a
number of companies plan to
market add-on units.
The BBC model A, as it stands, is
hardly capable of interfacing
anything, but once it has all the
sockets and plugs, it can be
attached to serial or parallel
printers, and a wide range of other
possibilities. But before adding
things outside the box. there is a
fair bit that actually adds on inside
the box:
• disk interface,
• speech synthesis,
• Econet interface,
• plug-in ROMs for extra
languages or toolkits
• ROM cartridge interface giving
professional programs, extra
speech vocabulary, alternative
characters sets etc.
Then, in separate add-on boxes you
will be able to get:
• teletext acquisition unit,
• Prestel acquisition unit,
• second processor - 6502 + 64k
RAM, Z80A + 64k RAM with
CP/M, or 16032 4- 128k RAM.
If you want to follow up this theme,
see the July issue of Personal
Computer World.
Having put forward the facts, let
me now give my own views. I don't
think it makes sense to try to say
one is 'better' than the other- it all
depends what you are looking for
and how much money you are
prepared to spend. If you only have
£125 in your pocket and want a
colour computer then Sinclair has
just what you are looking for! But
suppose you have £300 to spend,
is it necessarily better to go for the
machine with the broader
specification? I don't necessarily
think so. Do you really need all the
facilities the BBC machine offers?
**" you a re m „ ~~~"^" = **—
""SSSr^ %&"»* and
If you are a more experienced
programmer and want to write
structured programs, or think you
may need some of the expansion
features, then you would be better
to go for the BBC machine.
But if you are a complete
beginner wanting to learn to
program and to play a few games,
then I think you'd be better off with
a Spectrum, plus £1 75 to spend on
peripherals and software.
On the educational front, to do
anything other than use the
microcomputer as a demonstration
aid, you really need a decent pupil
to micro ratio. Therefore it is quite
tempting to compare the cost of ten
Spectrums with four BBC model A's
and decide you'd rather have a
pupil-micro ratio of 3 to 1 instead of
Vh to 1 . But there is a slight fallacy
ACORN USER SEPTEMBER
21
REVIEW
Si
Someone else has ULA problems
You may have heard about a
problem Sinclair found which
held up delivery of the first
Spectrums. Well apparently it
was a small problem with . . . yes,
you've guessed it, the ULA!
While the ULA was being re-
designed,and so as not to
disappoint the public, they have
sent the computers out with a
temporary modification. This
consists of a small integrated
circuit stuck onto the board with
double-sided adhesive tape.
Some of its legs are soldered
together, and others are joined
by bits of wire to a couple of the
legs of the ULA. This does not
seem to me to be an ideal way to
do a modification for production
machines, but I have been
assured by Mr Bill Nichols of
Sinclair Research that only 'a
small number of thousands' of
machines have gone out with
the temporary modification; that
so far they have not had any
machines sent back with faults
caused by the modification,
and that as soon as the new
ULAs become available they
will be put into all new
machines.
My main worry is that the
heat generated by the
voltage regulator will de-
grade the adhesive suffic-
iently for the chip to come
unstuck. It may move
around and short out on
other components. How-
ever, Mr Nichols assures
me that if this did
happen within the 12-
month guarantee, they
would be repaired free.
"rr«-
-
-
; .
**ltt
'tti
7.
«5 & P'S. ;;;
c
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in that argument. What about the
cost of the colour monitor or TV,
and the tape-recorder you will need
for each micro, and what about the
cost of software and of machine
maintenance?
Also what is the rest of
education going to do? If you swim
with the tide then there will be far
more support available, and far
more educational software. If you
look at the extra features available
on the BBC machine, it seems to
me that it is well worth the extra
£175. Then what about the Acorn
Electron? If that is going to be
software compatible with the BBC
machine and capable of linking
into the Econet, then that would
swing things further in favour of the
BBC machine.
The other educational factor to
be thought out is the Sinclair's
single key entry, and here I can
only give my own opinion. The
major point in favour of single key
entry, is not that it is easier for the
beginner to enter whole keywords
rather than typing them out on a
conventional keyboard. Indeed,
when each key has five or six
functions, it is debatable whether it
really is easier. Certainly for anyone
with experience of conventional
keyboards, it makes typing in
programs extremely slow and
laborious- at least initially.
But what does make the ZX
series more friendly to the beginner
is the fact that each line is checked
for syntax errors before it is
accepted.
My conclusion is that for the
beginner - especially of the
younger generation not yet
acquainted with a conventional
keyboard - nothing yet rivals the
Spectrum's price. This will be
The kids can
use the Spectrum
- 1 shall work
with the Beeb 55
doubly so if microdrives are on the
market some way before their
competitors. However, it will be
interesting to see what the Electron
will be like- I can only pass on the
vague rumours -coming from Acorn
Computers. I hear that it will have
32k ROM, 32k RAM, various modes
of graphics, though not as versatile
as the BBC machine, and that in
terms of price it will be a more
realistic rival to the Spectrum
When will it become available?
That I don't know. I would simply
say that if I were in Acorn's shoes I
would be pulling out all the stops
to get it into volume production for
Christmas. My feeling is that
Christmas 1982 will be an
extremely important time in the fight
for the UK market in small micros.
As far as education is
concerned, I don't think the
Spectrum has much of a chance -
but I may be wrong. It depends to
some extent on when the Electron
becomes available, and exactly
what features it has. In particular I
feel it is extremely important that it
should have an eight-bit port - not
just the address and data lines as
on the Spectrum and ZX81. In my
experience, schools are really
beginning to wake up to the
importance and potential in
educational terms of getting kids
wiring up their computers to the
outside world.
Spectrum versus BBC? - I hope
I've been able to put forward a few
helpful facts to help you compare
the two machines. It's up to you to
sort out what suits your pocket and
your application. In my household, I
shall be working on the BBC
machine and the kids can use the
Spectrum! #
22
ACORN USER SEPTEMBER
f
BBC Microcomputer System A's in stock now!
H
17
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** ■* » *_
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mmmm
2
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-000
wxv;o;^;<A;<iv:H:'*<'B< : i; : :g ; fl;
^•^
■£:&?***:£*:
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BBC
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«W.W^AMWMW^AW
V////////AVW-VW
#?:
We've got the BBC
Microcomputer Model A's in stock
- ready for immediate sale. Call in, try them out.
Official orders taken for Local Authorities. Schot
««•.
BBC Machines
Model 'A' £299
16K RAM 32K ROM. Full colour, high-
resolution graphics (+£7 p+p)
Model -B' 32K RAM 32K ROM £399
16 Colour graphics (+£7 p+p)
BBC Disk Interface £69
BBC B' Upgrade kit £130'
BBC Compatible Single Disk
Drive 100K bytes £235
(+£2.50 p+p)
BBC Compatible Dual Disk
Drive 200K bytes £389
(+£2.50 p+p)
14" RGB Colour Monitor (as usee »n the
BBC Computer programme) £279
(+£9.50 courier)
12" Green Monitor £95
(+£6.50 courier)
Cassette Player. Includes DIN to
DIN lead £28
Battery mains option (+£2 p+p)
BBCJoystick£13p.pair(+£lp+p)
' These onces include fitting send or bring
m your machine for upgrading.
BBC Software
The first of the software from
Acornsoft. Snapper, Defender,
Monster, Creative Graphics. Come
and review it!
Printers
Acorn GP80A Printer £199
Lowest ever price! (+£4.50 p+p)
Acorn GP100A Printer £228
(+£4.50 p+p)
Epson MX80 FT111 Printer New
model, dot matrix, high res. graphics
80 or 132 char's per line £431
(+£4.50 p+p)
All with free interface cable
Atoms
Atom kit £135
(+£3.50 p+p)
Colour Atom £199
Complete with 4 software cassettes
(+£3 p+p)
Atom Disk Pack £335
(+£2.50 p+p)
Atom Software
All the latest Acornsoft software in
stock. Atomcalc. electronic spread
sheet. FORTH, LISR Adventure etc.
Accessories for BBC
Computers
Listing paper, 2000 sheets £14
(+ £4 p+p)
Cassettes per 10 £4 (+ £1 p+p)
Disks, Dysan. top quality 5^" per 10
£28.75 (+ £1 p+p)
GP80andGP100 ribbon £4.75
(+ £1 p+p)
Printer Cable (parallel) £15
(+ £1 p+p)
6522 buffers £4.75 (+ £1 p+p)
DIN to DIN cassette leads £3.50
(+ £1 p+p)
BBC Machine dust covers £5.75
(+ £1 p+p)
Books
BBC 30 hour BASIC £5.50
(+£1 p+p)
Practical Programs for Atom & BBC
£5.95 (+£1 p+p)
BASIC Programming on the BBC
Micro £5.95 (+£1 p+p)
Programming the 6502 £11.75
(+ £1 p+p)
All the products are the official
versions, beware of imitations,
they will invalidate your guarantee.
-<— 3K*_*_
m
ALL PRICES INCLUDE VAT. FOR FURTHER fTlLrRn ARF Fl FnTRnmr^
DETAILS AND MAIL ORDER UST SEND LARGE SA.E. ^^^^^
Open Mon-Sat 9am 6pm.Thurs 9am-lpm teloi 959 7119 telex 881 3241
ACORN USER SEPTEMBER
23
NEC
T
Catering
for
motivated
minority
he 30 Hour Basic course
predates the BBC micro in
some senses. In 1980, the
National Extension College
decided that in view of the
growth of interest in mircocom-
puters, it should develop a
course in programming. The
college already had such
courses, but they were for
mainframe systems and were
declining in popularity. It was
clear that a course for home
owners of micros would have
more appeal.
So work started on a course
aimed at the home correspon-
dence student or students in
schemes run by local colleges.
Then in late 1980, the college
and the BBC became aware of
each other's activities.
Richard Freeman of the NEC explains
the history of 30 Hour Basic
A
,t that stage the BBC project
was little more than a title,
Hands on Micros and
everything was a total muddle.
It was computers for the
masses - hardware, program-
ming, applications, industrial
revival, education. There might
be a BBC book; there might be
a BBC computer. Bit if there
was a computer, would it be the
main feature of the series?
No one knew what computer
literacy meant - perhaps no
one yet does! But in the BBC
and NEC some people had long
associations with literacy (from
On the Move), numeracy (with
the NEC/YTV Make it Count
and Numbers At Work series
and the BBC It Figures series).
Was computer literacy like
that? And, more important, did
computer literacy mean being
able to program a computer?
This latter point was vital to
the project and remains crucial
to how educationists are
approaching the use of
computers in schools and
colleges. It is glibly said by
many - usually not owners of
micros - that soon there will be
a computer in every home. It is
then assumed that everyone
must learn to program a micro.
The first assumption is
probably false, the second
definitely so. Take the first: long
before most families get round
to purchasing a micro, they will
be offered cheap, intelligent
viewdata terminals. Once these
are available, most homes will
have no use for a separate
micro. Instead, the power of
many computers will be
available to people who own (or
rent) little more than a
keyboard.
The second false assumption
was more important to how
thoughts developed on the
NEC course. It requires only a
brief acquaintance with pro-
gramming to appreciate that
only a small proportion of the
population would ever find it
beneficial to learn programming.
They might program for interest
but there are few problems in
home life that justify writing
your own program.
o
nee that conclusion was
reached, the role of an NEC
course to accompany the BBC
series became clearer. If the
BBC series were to be
'computing for the masses', it
could not be more than
casually concerned with pro-
gramming. But the less it was
concerned with programming,
the more there needed to be
another part of the project that
provided the chance to learn
programming.
That was what the NEC was
planning before the BBC
discussions, so why all the
agonising about what to teach?
The answer lies in the highly
innovatory nature of the
project. No other nation has run
a computer literacy project so it
had to be carefully thought
through.
Having decided that the NEC
course should concentrate on
programming, the next question
was which language was it to
be? This was a decision the
BBC eventually made, opting
for Basic because most micros
provide it rather than, say,
Comal because most micros
ought to provide it. Without a
BBC micro, the language would
24
ACORN USER SEPTEMBER
NEC
have to have been Basic. What
has not been so clear to critics
is that even with a BBC micro,
the language still had to be
Basic. If it had been any other
choice, a mass appeal project
to interest all machine owners
would have become a buffs
corner for those who, by
definition, had no need of the
project.
X
.o settle on Basic was one
thing. To decide on a dialect,
quite another. Here we came
up against a classic problem of
collaborative projects. In early
1 981 , the BBC's schedules
necessitated fixing on a choice
of machine. But already the
NEC's schedules necessitated
that piloting of the course be
well on the way. So we wrote
and piloted the course using a
Superbrain. Then the timescales
of the NEC course and the BBC
micro became increasingly
incompatible. This became a
dominant factor in the dialect
decision. We started with the
assumption that once the BBC
Basic was clear, the course
would follow that Basic. But
after running two pilot version
of the course in a local college,
there was still no sign of a BBC
micro nor of a definitive
language. By May 1981, final
decisions had to be made at
NEC if an October publication
was to be kept to. (At that
stage, October 1981 was still
the BBC transmission date.) So
with no other choice, 30 Hour
Basic was going to have to go
to press at roughly the same
time as an emulator for the
BBC micro was to become
available.
X
.his then, by default, settled
the issue and we chose a
minimal version of Basic that
would run on most micros. Only
when the course was perfected
in that version was it checked
out on a BBC emulator so that
notes on BBC Basic could be
added.
The final 30 Hour Basic
course is a self-contained (but
add your own micro) course of
nine study units. It introduces
all the major features of Basic
Clive Prigmore, author of the
NEC book 30 Hour Basic
produced to complement the
BBC Computer Literacy
Project. Below, the College's
headquarter in Cambridge.
30 Hour Basic is available for
£5.50 (post free) from the
National Extension College,
1 8 Brooklands Avenue,
Cambridge, and from book-
shops. Two cassette tapes of
the programs in the courses
are available from the NEC,
£5.95 (post free) each. Many
local colleges run courses
based on the course. For
details write to BBC
Computer Literacy Project,
PO Box 7, London W3 6XJ.
up to and including simple file-
handling through a step-by-step
learning sequence. That in the
end has proved to be the
course's contribution to com-
puter education - its learning
structure. There are hundreds
of books that will tell you the
syntax of Basic, but few show
any sign of being written by
someone who appreciates the
problems of learning by
yourself - which is what the
NEC specialises in.
will not successfully extend to
200 lines. 30 Hour Basic lays
the foundation for this
extension.
i
T
he other major feature which
stands the course apart from
others is that it puts a heavy
emphasis on problem solving
and program structure. Be-
ginners may wonder why this is
necessary, and the answer lies
in what is beyond. Almost any
fool can string together 20 lines
of syntactically correct Basic
which run. But unless those
lines are programmed against a
clear understanding of the
need for good structure, they
t is too early to evaluate the
course and its contribution to
the BBC project or to
programming education but
some points can be made.
First, we were right about
dialect - we were pushed into
producing a Sinclair ZX81
edition which has sold in
enormous quantities.
Second, we were right to
assume that amongst the BBC
audience there would be a
motivated minority who would
wish to master programming.
They do not just want an
acquaintance with program-
ming, but to solve real
problems. These are the people
who have chosen to take the
course and they would have felt
cheated with anything less
substantial than we have given
them.
ACORN USER SEPTEMBER
25
OFF BECOKWH
The London ACORN-BBC Centre
Suppliers to Schools and Colleges
Atom
BBC
Printers
Cassettes
Monitors
Software
Accessories
Also
: FREE 1 0K upgrade with every Atome purchased.
Utility ROM page modules now in stock.
: Main Dealers & Service Centre. Models A and B
in stock. Memory up-grades (HM 4816 AP-3)
£26.99.
: Epson £345. Oki £295. Seikosha £209. Setting
up for BBC free.
: BBC-matched cassette recorders £32.
: 1 2" 1 8Mhz green screen monochrome £99.
14" colour £229.
:Acornsoft, Bug-byte, CP/M.
: Tapes, listing paper, forms, chips, sockets,
diskettes, components, add-ons.
: TORCH, NASCOM, GEMINI, GALAXY,
QUANTUM, IOTECC, MICROPROFESSOR.
Add 1 5% VAT to all prices. Carriage extra.
BR CLAPHAM
JUNCTION
ST JOHN'S HILL
LAVENDER HILL
(SOUTH CIRCULAR)
BATTERSEA RISE,
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Easy parking
4 minutes from BR
Clapham Junction
Bus: 19,37,39,45.49,68
77.170.249
Tube: Clapham Common
Tel: 01-223 7730
Open Daily:
9.30 AM - 7 PM
QBE
Colossal Adventure .. 16K/32K .. £8/£10
The classic mainframe game "Adventure" with all
treasures and creatures of the original. And with 70
extra rooms!
Adventure Quest .. 16K/32K .. £8/£10
From the great forest, up ore mountain, braving fire,,
marsh and darkness on a quest against Tyranny. Face
vampires, demons, wizards, 200-foot worms . . .
Adventure games are fascinating. You enter English
phrases and the computer acts as a window to worlds
of magic.
Every Level 9 adventure has over 200 individually
described locations and a game may take weeks to
solve! Only our combination of data and code
compaction allows so much to be provided.
FREE P&P. NO VAT. Money back if unhappy.
Supplied on TDK cassettes. Send order, describing
your computer, or a SAE for full details of all our
BBCpu games to:
LEVEL 9 COMPUTING
229 Hughenden Road, High Wycombe, Bucks
Looking for an ACORN dealer in the
WEST OF
SCOTLAND?
then why not visit us?
We have a full range of software by:-
ACORN SOFT
BUG- BYTE
PROGRAM POWER
for the ATOM and BBC micros
We also stock RAM chips and can
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ATOM and BBC micros.
PERSONAL
COMPUTERS
20 Wellington Square, Ayr.
Telephone: Ayr 285082
Oakleaf Computers
JvQS* 9
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Education Hobbyist &
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onanOAKTREE
WORKSTATION
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With a built-in accessory drawerJ
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TWIN USER JOYSTICK INTERFACE ATOM/BBC E1 3.95
[Protect the keyboard of your computer by interfacing
"Atari" joysticks to it. The joysticks plug into the interface
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£3.99 if ordered with the interface). Now two people cai
successfully play games or one person can have,
jjiore control over the computer. Ful
.software supplied.
ATOM LATEST
It Atom have made it, we
stock it. Disk drives off
the shelf. Hardware,
books, printers.
Phone now. Prices
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BBC UPGRADES
Full or partial upgrades,
memories, printers or|
disk interfaces etc. All
in stock. Prices dropping.
Phone for quotation.
All current BBCI
peripherals stocked.
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Please send your remittance to:
1 21 DUDLEY ROAD GRANTHAM,
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specialists TELEPHONE: (0476) 76994
26
ACORN USER SEPTEMBER
JOIN THE REVOLUTION
T,
his article is not exactly about
how to make art with a BBC
computer. That problem is no
different from the more general one
that every art student, great artist or
weekend painter is faced with: how
to make art at all.
We should distinguish between
images and art. Just because you
can have fun with random numbers
or spirals on a TV screen, that
doesn't necessarily make very
significant art. So this piece sets
out to do three things.
First, we'll look at the general
context for art done by, with, or
sometimes in spite of, computers.
Second, we'll examine some of the
possibilities the BBC microcomputer
suggests: what are its special
characteristics? Finally, there are a
few suggestions, pointers towards
what you might consider doing,
using your computer, to make art.
So-called 'computer-art' has
been going for about 30 years -
ever since computers became
available. But most of the work has
been done by people who were
often better at computing than art.
Art isn't as simple as
making pretty pictures
on a screen, says
Brian Reffin Smith.
He points
the way and
outlines some
possibilities the
BBC micro suggests
A mathematical formula or
transformation that produced an
interesting-looking graph or perhaps
a whirling spiral, was seized upon,
framed on the wall, and labelled
'art'. It is arguable, though, that if it
had been done with a Spirograph,
or by doodling with eyes shut,
people would hardly have given it a
glance.
s
'o if we are interested in what
computers in general, and the BBC
micro in particular, can do to help
us make art, we have a dual
responsibility. Not only must we get
the computing right, but also the art
should, at the very least, not bore
rigid those who just see it, having
missed the (very wonderful, no
doubt) process that created it.
Ah! But there's a thought!
Perhaps if we actually made the
process itself the artwork . . . then
people could get more involved.
Well - yes. And some of the most
celebrated pieces of technological
art have made quite clear, and have
actually used, the process and
systems 'behind' the artwork.
rn
lake Edward Ihnatowicz's famous
'Senster' shown overleaf. This piece
of -what, sculpture? - was quite
clearly a mechanical device, linked
to a computer. It vaguely
resembled a 3-legged pneumatically-
powered giraffe, but all its workings
ACORN USER SEPTEMBER
27
ART
Senster vaguely
resembled a
three-legged,
pneumatically-powered
giraffe, with all
its workings visible
were visible. The computer was
programmed to make the thing go
towards gentle movements or
sounds, but to avoid violent moves
or loud cries.
It used microphone 'ears', and
radar 'eyes'. Perhaps just because
there was a conflict between what it
looked like (technological) and how
it acted (animal-like), people would
stand and watch it for hours at a
time. Yet the program in the
computer was, in essence, simpler
than most graphics programs.
V^erald Hushlak is a Canadian
artist who often uses computer
graphics in his works. Living in
Calgary, a city rich in graphics
information technology because of
the oil exploration boom (oil
companies need to visualise
masses of data), he has access to
some very sophisticated equipment.
But the techniques he uses are
available to anyone with a BBC
machine and the imagination.
Briefly, he gets the computer to
construct an image that is partly
random, partly made up of
predefined elements. This is
processed in such a way as to
produce a whole series of images,
each bearing some relationship to
the one before, and also to the
totality of images. Elements are
enlarged, reduced, moved around,
combined . . . and again, the
'thinking' (his and the computer's)
is made visible.
His work does not rely on a
single image - none of the
individual frames might be thought
particularly stunning - but it is the
process of production that he
exhibits.
Xiere, at last, is where we, with
small computers, can score heavily.
For virtually anything we choose to
do with the machine is, by
definition, all process! We have to
lay open the series of events and
decisions which we will use to
achieve some result -because that
is the program. We may attempt to
conceal it from others, but we
ourselves cannot possibly avoid it.
Let's consider some of the things
the BBC computer can do, that we
can use - sticking as closely as
possible to that idea of process.
Process implies change, and the
powerful graphics of the BBC
machine are just what we need. In
the old days, you could just light up
parts of the screen, individual
'pixels'. Then - wonder of wonders -
you could draw lines!
But now, we have the choice of
at least 47 ways of drawing
anything: that being the number of
different PLOT commands
Suppose we have, incorporated in
a program as a series of DATA
statements, numbers specifying the
horizontal and vertical co-ordinates
of a series of lines.
i
f we draw those out using DRAW
ie PLOT 5), we get a line shape, in
whatever colour we choose. But
let's see what else we can do - and
imagine the resulting images being
photographed, framed, and gradually
building up into a huge series for
our retrospective show at the New
York Museum of Modern Art (well
why not?)
Suppose we use PLOT 1 instead
of DRAW. This draws a line
'relative', in the current colour. This
means that the x and y values of
the line's endpoint are not
measured on the screen like a
piece of graph-paper, from the 0,0
origin at bottom left, but are added
on to the measurements of the last
point. In other words, if we were last
'at' 40, 50, and the new line is PLOT
1 ,1 00, 1 00 then a line will be drawn
to position 140, 150. This will then
be the starting position for the next
line, and so on.
As
an amazingly difficult exercise
(humans weren't built for this kind
of thing!) try to imagine a simple
shape (say a square) drawn out in
the ordinary way, and then using
PLOT 1 . What happens to it?
Picking almost at random from
the list of PLOT commands in the
BBC manual, we might then try
PLOT 86. This not only draws a
solid triangle between the last three
points Visited', it also does it in the
logically inverse colour to what was
already there. And by use of the
GCOL command, we can choose to
draw in 'exclusive of mode
(immediately doubling the 47
options.)
So not only do parts of the
drawing become solid (and
probably not like we'd imagine,
either), but also the colours change
when the solid areas overlap.
This is advanced stuff - I mean
the art, not the graphics; see how
we've really got things going for
us? What we've done is to
restructure the relationships between
28
ACORN USER SEPTEMBER
ART
the various parts of the image. No
longer does line follow line, like a
history book or a story, in a linear
way.
Instead, parts of the image
interact with previous parts, where
the triangles overlap, spilling out of
the sparse, thin little lines. And all
by changing PLOT 1 to PLOT 86!
T h
.his is of some interest, even if
you consider the drawing just as a
picture. But think! A picture must
be of something. So it isn't just
lines or bits of colour we're altering
- it's actually little, bits and pieces
of meaning. If you want an analogy,
the lines themselves are just like
the sounds in the words used to tell
a story - but who ever remembered
a good story because of the W
sound in 'wolf? It's the story's
meaning that counts, and whether
Little Red Riding Hood got eaten or
not.
When I began this piece, I
thought that I'd be mentioning all
sorts of PLOT commands, routines
for doing this and that, maybe show
a photo of an image produced by a
short program. But really, that's
unnecessary. For the truth is, there
are so many good articles around
on how PLOT works; and lots of
programs that will make circles or
move squares. The BBC manual
itself - the revised version - is
pretty good too.
So I ended up by just trying to
tell you about one or two of the
things that I think are really
important in making art with a
computer. See if you agree.
A
nother point is that 'really 1 , the art
doesn't matter much either. It's the
ideas, and how they change us,
that matter. There's never been
such a potentially powerful
combination, to do things like that,
as you and your computer.
If there are two categories of
people that can get away with
almost anything (for all the wrong
reasons, I know, but let's use it!) it's
artists and computer people.
So welcome to the revolution.
(Technological? Art? Political? If
you can separate them, you
choose.) $
Brian Reffin Smith works in
the Royal College of Art's
design research department.
He wrote the BBC software on
Drawing and Painting, now
available. Although simple,
these will help develop the
techniques in this article. The
Painting package simulates
air-brushing and produces
three-dimensional effects. The
Drawing software explores
shapes, patterns and colour.
Details of the Painting and
Drawing cassettes can be
obtained from BBC Publications
at 35 Marylebone High
Street, London W1 M 4AA.
They run on both model A
and B machines.
5
%
5
'.—■*"' • - — -"--~."^j'
it ^ m
,--
• ■
.--'.-.,-_•■ :
■ -■•■* / '.. ■ <.. .*-->. ft ■■'.
L. .-■-■-.. ---.- fh< Ti;**
1 /. ■■'-
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Hushlak. .graphics use sophisticated equipment, but his techniques are open to all
ACORN USER SEPTEMBER
29
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FOR COMPUTERS &
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The BBC and Acorn dealer for
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Essential reading for all computers
FORTH THEORYAND PRACTICE
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Two books from Acornsoft that provide a
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LISP and FORTH. Many practical examples
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Most of the contents of the manuals are
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Both manuals are spiral bound to lie flat and
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Each manual costs £6 including post and
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Credit Card Holders can ring 0223 316039
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.JS*H i — ^^ikW***
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a
30
ACORN USER SEPTEMBER
I NTS AND TIPS
= Wake up to the=
SOUND of MUSIC
aking sounds with the BBC
cro is easy - despite what you
may have heard. The harder part is
to turn the noise into music. The
last issue covered sound effects, so
here we experiment with notes;
playing tunes and turning your
keyboard into an organ.
The SOUND command has four
major parameters: voice control C;
amplitude, A; pitch control P;
duration D. It can be expressed in
terms of these parameters as
SOUND C, A, P, D.
In its simplest form, the voice
control can be in any channel from
to 3, the amplitude (volume) may
be a value from to -15, the pitch
control may be a note from to
255 and the duration may be a time
in units of 1/20 s from to 255. So:
Sound 3, -15, 101, 20
will play voice 3 at full volume on
top C for one second.
B
efore we can produce notes, we
need to know the relationship
between the pitch control numbers
and the actual notes played, which
is shown overleaf. Apart from the
lowest note (A#) with value 0, the
remainder of the notes have a gap
of 4 units per semitone. This
arithmetic sequence indicates that
octaves will occur at intervals of 48
ie (gap of 4 multiplied by 12
semitones in an octave). Program 1
uses the simple SOUND command
to generate the 12 semitones of a
chromatic octave from middle C.
By altering the 53s in line 20, it
would be possible to play a
chromatic octave from any note.
For example from G, simply
exchange the 53s for 81 s.
Even if you're not Mozart, writing
music is fun on the BBC micro.
This month Joe Telford gives you
some ideas on playing tunes and
using the keyboard as an organ.
JLo further consider the production
of scales, look at program 2. The
gaps between notes in major
octaves are regarded as whole
tones or semitones, and a complete
scale is made up of the
combination of tones (T) and
semitones (S) of line 20. The * is
simply a reference point for the first
note and could have been any
symbol (other than T). Line 60
examines which type of gap (T or S)
is being played and increments the
note value by four, so tones have
gaps of eight while semitones are
gapped as 4. We can play a scale
in any key - input 53 in response to
line 30 gives the key of C, while a
value of 73 would give F major and
61 would give D major.
this, the voice control parameter
should be regarded as a 4-byte
hexadecimal number (hence the &
prefix).
X
L
et us look again at the voice
control parameter of the SOUND
command. Type this simple
program.
NEW
10SOUND1,-15,53,20
20 SOUND 2,-15,69,20
30 SOUND3, -15, 81,20
RUN
The result is a fairly pleasant,
though slightly fuzzy chord in C
major (C. E, G). Now replace line 1
with:
10 SOUND &0201, -15, 53,20
and run the program. Now we have
a much crisper chord. To explain
he four bytes from which this
number is constructed are labelled
&HSFC. The most significant byte is
labelled H for maintain. It is set to
for normal SOUND statements, but
could be set to 1 if an envelope is
in use. In this case the final stages
of the previous note would be
maintained under envelope control
while the note containing H would
not sound.
Jjyte 3-S- produced the crisp
chord above. When set to 0, each
note is sounded depending on its
place in the sound queue, hence 2
voices sounded in order appear
slightly fuzzy. Because S is a
mnemonic for synchronise, setting
S as follows causes the effects
overleaf
Program 1
I0 fiE* H*rg ?g"8!**«l STEP
af> NEXT
progra 01 2
l0 REH STANDARD OCT^f.
iw« «V5 V
tart
40 FOR nor.e
-O REM Tm.^V THSW na-.i
*.rt IF value"- '-,
„ 90OWO l,-iS,not e ,r
8 NE*T
• 1
ACORN USER SEPTEMBER
31
B
I
80TTOM
c
5
D
13
E
21
F
25
G
33
A
fl
B
+9
MIDDLE
c
53
D
61
E
&9
F
73
G
81
A
B
V
TOP
C
101
D
\0°)
E
"7
S = voices take their turn in
the queue.
S = 1 this voice and next voice
sound together.
S = 2 this voice and next 2
voices sound together.
S = 3 this voice and next 3
voices sound together.
Byte 2 is normally set to when it
allows the next note to play its full
length. If set to 1, all sounds in the
queue are removed and the note
containing this byte is played
immediately.
x
.he final byte C for channel is the
easiest to understand. It can take
the values 0, 1, 2, 3 and refers to
the voice to be sounded. The
parameters &HSFC can be used in
any combination although &FC
combinations and &SFC combin-
ations especially are dealt with in
this article.
T
he SOUND command is a good
example of the actual parameters
for a musical note. We have
Program 3
10 REM FAIR ENOUGH
|o REM CONVERT TU*JP
40 MH P"CH AND U*
tssssrsiio ■ ***** —■
'Z "VS- ^« ■»'* » NumBBS
26 SOUNDS - 3, no £-jJ t| .n-te^n
270 SOUNDS.- S."»" doriltlo n»t«-P«
-8" SOUNDS. -«• not*. -«,
-OO SOiWDl.O.note.-
300 SOUNDZ.O.not-.-
I Saw"-.
T Q - SOUND1. 0,0.30
380 XTSfiKT DATA POSTER TO
SETS mm «*T VERSE
«0
430
nCIKT verse
Note Nam©
Duration
K semiquaver
2
\ doited semiquaver
3
N quaver
A
Jl dotted quaver
crotchet
6
6
dolled crotchet
minim
dotted minim
12
16
24
Figure 1 .
Note the
duration of
each note.
ffc -mi breve
32
examined the voice parameter and
the pitch parameter, but before we
produce musical tunes we need to
examine the duration of each note.
Figure 1 gives a list of
parameters for duration referring to
commonly used time values. So:
SOUND2,-15, 101,8
would play top C as a crotchet (at a
rate of 150 crotchets per minute).
Th
he best source of 'easy to
convert' tunes is simple organ
books. The first stage of conversion
is to write each tune as letters, then
use the art work above to convert to
numbers. To each pitch number
thus found we make up a pair by
adding the duration of the note as
found by using the keyboard given
above. The next stage is to write the
pitch duration pairs into DATA
statements from which a program
can produce a tune. Examine
program 3, which plays a particular
tune, found in the DATA statements
of lines 60 to 130. Replacing the
numbers with your own would
change the tune. It is useful to end
each tune with a value which the
computer can easily check, hence
the-1 data at line 150.
Because tunes have different
tempos or speeds, although they
may all have quavers, we may need
to speed up or slow down every
duration code by the same factor.
Line 170 sets the tempo to 0.75
which slightly speeds up the tune.
Experiment with values for the
tempo of 0.5, 1 , or 2, to achieve the
best result.
Although the program is well
explained by REM statements it is
worth examining the SOUND
commands. To gain a pure single
sound, lines 270, 280, 300, 310,
370, and 380 can be omitted.
However, their inclusion with voice
2 playing bass (note -48) and voice
3 playing high octaves (note +96)
and without the T parameter of the
voice command being set, gives an
old-fashioned fairground organ
sound. Lines 290 to 320 are
essential to separate notes with
short gaps of silence. Remove lines
290 to 320 to fully appreciate their
value. Lines 360 to 380 give a
rather longer silence at the end of
each verse.
E
inally, the number of verses can
be altered at line 190. There is a
great deal of value in this type of
program as it can be adapted to
any tune. Unfortunately it has two
main faults. The first is that at the
end of musical phrases there is
normally a slight pause - but not in
program 3. The second is that
program 3 cannot play accented
notes. An accented note is a note
played at a louder volume for
Program 4
K l»TA-t3,61,B,-13,**>">
50 DATA -1>-W"*
*0 FOR v«r*e *• * duration
g if not.- !?S£ ( d U rrttt
ftO SOUND! ,0, not**-
30 GOT0210
jAO SQUNDi .0,0,7°
41 RESTORE
flV MERT vers*
:«fftp<
32
ACORN USER SEPTEMBER
12?
A
137
B
14-5
4-TH
OCTAVE
c
1+9
D
157
E
165
F
6
'77
A
185
B
193
STH
OCTAVE
197
D
lOS
E
213
F
A
233
B
2+5"
D
253
emphasis. Try clapping the rhythm
of 'Jack and Jill went up the hill' to
hear the accents on certain beats.
To bring the BBC micro's sound
production closer to music
performed live by people, it is
necessary to rectify both these
faults.
One solution is found in program
4, where we enter 3 figures for data
on each note:
• volume (-12 for normal and -13
for accent),
• pitch (as program 3),
• duration (as program 3 except in
some cases where I finally got
my dotted crotchets correct).
Some lines (eg 75) contain an 0, 0,
8 DATA statement which effectively
says 'rest for a crotchet of time',
and occurs at the end of musical
phrases.
JVJLoving on from this area of
canned music, the BBC micro can
be a very versatile musical
instrument for live performances.
Program 5 is my attempt to improve
on the organ of the Welcome Pack.
However, I have made no attempt
to produce colours to match.
Two main problems exist when
using the BBC machine as a
keyboard instrument. The first is
that each note sounds for a set
length of time, and the second is
Program 5
gen R ^ys B iJ°cSBor«tic order
REM SET REPEAT RATES
t' '11 '.
; S M M £ gays!?
> RE« KM? FOR NOTE
S 5 l SG33' THEN «l-f©
so soundm >." al "*°- t ' 1
£ ^"jSw" «** 80 RE66T KEVBO^D
; 70 «pxi3 7
:S ?2*6»32
fiSSS
fk ■: r.& ytfo. .^T tt$K
GJrSl^jf^ [^4^1
e/d
N/A M/fe </c >/d ?/E
Figure 2. Diagram of keys used in organ program.
Switching between octaves is done using Shift lock.
that because of the type-ahead
facility on the keyboard, notes can
play on long after fingers have
been removed from the keys.
Shortening the note duration and
relying on the auto repeat facility
gave a drill-like effect, as in my
prototype program.
The solution was to adjust the
repeat rate - as detailed in the
previous edition to give a fast
repeat instantly, (lines 70, 80) and
then to use the &IV parameter (lines
210-230) so that sound was
continuous but the effect of
stopping playing was instantaneous.
x
.he program generates my
fairground organ over a good two
octaves range, changeable from
lower to upper octaves via the shift
lock key. Because of the
adjustment to repeat rates they are
reset on ERROR or on ESCAPE.
Look at figure 2. This gives the
layout of the keys used for each
octave so that 'z/C means lower
case z plays a C in the lower
octave, while 7/E' means ? plays
an E in the upper octaves with shift
key down.
Figure 2 will therefore let you
convert music from a tune book to
the keys of your BBC micro. By way
of starting off a BBC tunebook, I
offer figure 3 as tune no 1. Make
sure the shift lock LED is lit, then
play the notes shown - you should
pick up the rhythm quickly as the
tune seems to be fairly well known.
JC/nvelopes, as the name suggests,
are useful ways of packaging
sounds so that the waveform has
an overall shape. The ENVELOPE
command is a convenient way of
controlling both pitch and volume
of a sound, though its use requires
careful forethought. It is followed by
1 4 parameters:
ENVELOPE N, T, P1 1 , P12, P13,
PN1, PN2, PN3, AA, AD, AS, AR,
ALA, ALD
The ENVELOPE commands only
appear to work during a SOUND
command, so that SOUND 1, 4,
1 01 , 20 plays voice 1 with the basic
frequency of top C for one second.
During that second it is under
control of envelope 4. You can
generate up to 4 envelopes to work
simultaneously, numbered 1 to 4 in
parameter N of the ENVELOPE
Z X C V V
V V V V
V
C
Z X C V V
V B B N
N N N J J
B V B N
B
V
Z Z Z X C
V
< < N < <
N < > <
J
N
J J B J J
B J <
< < N < <
N < > <
J
N
N B V Z V
C V B V
X Z
Figure 3. Play notes on these
keys with Shift lock LED lit,
ACORN USER SEPTEMBER
33
HINTS AND TIPS
command, and matched by 1 to 4
in the volume section of the
SOUND command.
Look at figure 4. This is an
amplitude waveform common to the
BBC ENVELOPE statement. It
consists of 4 ranges marked attack
(A A), decay (AD), sustain (AS), and
release (AR), as well as two set
points (ALA) -volume after attack
ramp and ALD, -volume after decay
ramp. The volume levels ALA and
ALD are numbers between and
126. To produce a useful envelope
consideration has to be given to
the type of instrument to be
imitated. Look at figure 5 which is
the amplitude envelope of a
percussive piano-like instrument
Note the steep gradient of the
attack ramp - giving the note bite,
and the gentler slope of the decay,
sustain, and release ramps, giving
the fading sound of a piano note.
The command to produce this is:
ENVELOPE 1. 0, 0, 0, 0,
126,-4, 0,-1,126, 100
0. 0,
Program 6
fi£!1 ROUND
> DATAI6.4B,fl.K.a-^ ! *
ui2a v w
.40
*
i-£i
52,4. 4S
4,60
32, 16p32i
270
DHffM,32,B,«0,4i*"'
Drt TA4,32.4,49,e
DATA 32.6,12**"
REn ,„AT MUCH LIST 5™CE
JKKTBS'iSS'iSi,.
, R £M keep TJ«-
Jf JoiCE I NOU FINISHED PUT
J M« VOICE 2 CONCLUDES
ROUND .
S0UND2.1.P>TCH
f*E»T
ni*«,'VHEni
■ Nl
Vf/WrW
*IA 13
Volume
ALA
T/me as on SOUND statement
Figure 4. Amplitude waveform common to ENVELOPE statement.
The first parameter N, is 1, the
envelope number. The second
parameter T, is the time per step in
1/100s. (Plus an extra 1/1 00s. In
this case = 1/1 00s.) The next six
zeros would be the pitch envelope.
The next number, 126, is parameter
AA. Combined with the parameter T
and volume level ALA we create an
attack ramp which increases at a
volume (AA) of 126 per 1/1 00s (T)
up to a maximum of 1 26 (ALA).
Th
he next parameter is AD, the
decay rate. The combination of
parameters around this is T, AD,
and ALD (the last parameter, 100).
The decay ramp decreases to 100
(ALD) at a volume rate of -4 (AD)
per 1/1 00th sec (T). The note then
is sustained at that level (AS=0)
until the time set in the sound
statement runs out. The note then
releases at a volume rate of -1 per
1/1 00s (T), and ceases sounding.
.f further notes follow an envelope-
controlled note, the release stage is
cancelled. The next note starts
immediately after the preceeding
one has been held for the time set
in its SOUND command. I'll let you
consider figure 6, which is a totally
different envelope, reminiscent of
an accordian or mouth-organ. It is
generated by the statement:
ENVELOPE 2, 1, 0, 0, 0, 0, 0, 0,
60,10,0,-60,60,120
Using the programs developed in
this article, experiment with the
amplitude envelopes. Enter them as
low-numbered line numbers and
alter the volume parameter of each
sound statement to indicate the
envelope waveform required.
The next stage is to move on to
designing your own amplitude
envelopes. The only warning is to
keep off the six pitch parameters
until you know what you are doing.
Beware also, an envelope with AS
and AR parameters set to 0, can
sound permanently. To prove this
micro is the beeb's knees, I include
program 6 which uses the
ENVELOPE and SOUND statements
to play a round. Here, two voices
play the same tune starting at
slightly different times. The program
is well REM'd so should not be too
difficult to follow.
Next issue: pitch envelope and
moving graphics. $
f'SiL-TH:
AR-1
r.™
4 tf'tOOs appro*
I^'ICOS
WQQ*
t Qv*Y*t
Figure 5. Percussive amplitude envelope given by
ENVELOPE 1,0, 0,0, 0,0,0, O, 126,-4,0,-1, 126, 100.
Figure 6. Reeded amplitude envelope given by
ENVELOPE 2, 1, O, O, O, O, O, O, 60, 10, 0,-60, 60,
120.
34
ACORN USER SEPTEMBER
Home micro LUorh Station
Computing Comfort, Convenience and Control in your
Living Room with this Specially Designed Work Station
Armchair height for easy keyboarding
Attractive scratch resistant finish looks good in any living room
Includes 4 -gang power socket to do away with trailing wires
Convenient drawer for manuals etc., fitted with cassette storage rack
Easily assembled flat pack
THIS EXCLUSIVE MAIL ORDER OFFER AT ONLY £49.95 (+£7 carriage)
And because we think your Microcomputer should be protected from damaging dust particles we are including a fitted Micro
Cover FREE with every Work Station. This reinforced VINYL DUST COVER with wiring cut out at rear is AVAILABLE
SEPARATELY at £2.95 incl., P&P
TO: EARLCAPE LTD., LOWFIELDS ROAD, LEEDS LS12 6BT
Please send me Micro Work Station(s) at £56.95 incl VAT and carriage (UK Mainland only)
I enclose cheque for or charge my Access Account Number
SIGNATURE
Please send me Micro Dust Cover(s)
at £2.95 including P& P (state model)
I enclose cheque/postal order for £
Please allow 28 days for delivery of Work Station
NAME
ADDRESS
ACORN USER SEPTEMBER
35
ATOM EXTRA
The disc pack manual
does not tell all about
these useful features
The Atom disk pack provides
several capabilities which were not
documented in the initial disk pack
manual. These include the ability to
keep a record of all information
printed to the screen on the disk,
and to store on the disk a set of
commands which can then be
obeyed as if they were typed in at
the keyboard. Also not mentioned
was a VERIFY command which is
documented here. The last
undocumented feature is the
software to drive the Acorn 40-
character VDU card from the Atom.
The command *SPOOL "name"
opens a file of the given name and
all characters subsequently printed
to the VDU system are also stored
in this file using ASCII. The
spooling of characters to a file is
stopped by using the *SHUT
command. Examples will probably
make this clearer.
Characters can appear on the
screen in several ways:
• as a result of a print statement in
a Basic program.
• when a character is typed at the
keyboard.
• as a result of some command in
Basic or the operating system
(eg, LISTor*CAT).
All these characters will end up in
the spool file if one is opened. One
important point is that the carriage
return and line feed codes sent to
the screen at the end of each line
of a Basic listing will also end
on the spool file. For example,
10 *SPOOL "Example"
20 PRINT "1234567890"
30 *SHUT
40 END
up
5 P.$2
10 A = FIN "Program"
20 DO
30 P. $BGETA
40 UNTIL PIRA= EXTA
50 P.S3
60 END
Hence a record can be made of the
output from the computer for
subsequent printing, or exam-
ination by another program.
The *EXEC "name" command is
a complimentary utility to SPOOL
which gets bytes from a serial file
on disk and enters them to the
computer as if they had been typed
at the keyboard. Hence doing an
EXEC on the file "Example" created
as in the description of spool would
go as follows:
*EXEC "Example"
1234567890
and because there was no carriage
return stored in the spool file, you
would have to hit return to get the
prompt back.
A
will create a file containing the
following bytes in hex: 31 32 33 34
35 36 37 38 39 30, whereas the
sequence:
>*SPOOL "Program"
>LIST
10 *SPOOL "Example"
20 PRINT "1234567890"
30*SHUT
40 END
>*SHUT
will create a file with the ASCII
codes for the Basic prompt and the
characters LIST followed by the
bytes OA and OD which are the
codes for line-feed and carriage
return. Next in the file will be the
codes for the next line which
consists of some spaces followed
by characters 1 and 0, a space and
so on until the line-feed and
carriage return at the end of this
line. This continues including the
codes, for SHU and T and a final
line-feed before the spool file is
closed.
^^ontents of a spool file can be
examined or printed to the printer
by a program such as:
sequence of common commands
can be stored as a file to be
EXECed.
*LOAD "Data" 8200
?18 = #28
LOAD "Program"
RUN
To type this in every time would be
tedious, so an EXEC file could be
created using the following
program.
10 A = FIN "Start"
20 SPUT A, ,4 *LOAD""Data""8200"
30 SPUTA, "?1 8 = #28"
40 SPUT A, "LOAD""Program"""
50 SPUTA, "RUN"
60 SHUT A
70 END
After this has been done, the
program can be started by typing
the *EXEC START command.
Another use of the EXEC file is
to merge Basic programs.
A program similar to the one
above could be used to create a
file containing a few lines of Basic
including line numbers and when
the file was EXECed, the lines
would be added to any Basic
programs already in the current text
space. If line numbers are
duplicated, the lines in the EXEC
file overwrite the lines in the
program, so care must be taken.
36
ACORN USER SEPTEMBER
ATOM EXTRA
Program 1
1
REM*** ********* ***************
70
d
2
REM (C) ACORN COMPUTERS (1982)
75
B=H!E&M;<3=H!(E+2)&M;W=H!CE+4)&M+(H?(E+6)/l6)*M
3
REM****'***********************
80
T^(H?(E+6)&15)*256+H?(E+7)
5
REM NO RECOMENDATION IS GIVEN
85
R=W/256;IFW&255< >0;R-R+1
6
REM OR IMPLIED AS THE USE OF
90
IFF<T;P. "BLANK "F T-F; A=F;C=T-1 ;X=1 00;G.r
7
REM ANY OF THE ROUTINES USED
100
IFE-0;END
8
REM IN THIS PROGRAM FOR ANY
110
FOR O=0TO6
9
REM OTHER PURPOSE
120
P.S(0?(L+E));N.
10
STOP="P. '""ERROR IN CATALOGUE SECTOR 1 OR
2"";END" 125
P. &B,&Q,&W,T,R
12
?1 6=TOP; ?1 7=TOP/256; *CAT
126
A=T ;C=T+R-1
13
@=5
127
IF R^0;G.190
15
M=ttFFFF;U=39C
130
X=1 90 ; G . r
20
L=#2000;H=82100
190
E=E-8
30
N=H?5
200
IFE)=0;G.d
32
P. '"NUMBER OF ENTRIES"N/8
300
END
35
P.'
1130
rF=A
45
P,'
1135
LINK8E75B
50
S=(H?6fil5)*256+H?7
1140
!U=«A000
55
P. "SECTORS" S'
1150
U?4=0;U?5=1 ;U?6=F/256;U?7=F
56
P. '"NAME STRT EXEC LENGTH SSEC SEC"
1153
P.S21
60
E=N
1155
STOP="G.s"
65
F=2
1 156
1157
Y=! 16;?16--TOP;?17=TOP/256
REMLINK SE567
An alternative method of creating
an EXEC file for a routine is to
spool a copy of the required
routine. If we have a program with a
routine between lines 2000 and
3000 that we want to use;
>*SPOOL "Section"
>LIST 2000,3000
2000 ---
2900 ---
>*SHUT
The file created will contain the
>LIST and > *SHUT lines which
will cause errors when the file is
EXECed in, but this will not be a
problem. The file however, also
contains line-feed characters which
must be removed. The following
program will create a new file
called ROUTINE with the line-feeds
removed.
10 A= FIN "Section"
20 B = FOUT "Routine"
30 E =0
40 DO
50 D = BGET A
60 IF D = 13; IF E = 10;
PTRB = PTRB-1
70 BPUT B,D
80 E = D
90 UNTIL PIRA > = EXTA
100 SHUT A
110 SHUT B
120 END
It is then possible to use the EXEC
command to add this routine to
your programs.
Another command can be used to
redirect all screen output to a set of
routines in the disk pack which
drives the Acorn 40-character
Prestel character set VDU. This
card from Acorn can be connected
inside this Atom with a suitable
power supply and will provide a 40
character by 25 line screen display
on a colour monitor. Further details
can be found in the Acorn
Computer Systems brochure.
Output will be sent to the 40
character VDU following "VDU 1
and to the normal Acorn screen
following *VDU 0.
The verify utility (program 1) is
written in Basic to run on the Atom
in conjunction with the Atom disk
pack. The program will attempt to
verify all the sectors on a disk
inserted in the drive indicating
which files any corrupted sectors
are in. The disk to be verified
should be inserted in the drive
before the program is run.
The program will first attempt to
load the catalogue of the disk. This
is stored on the disk in two sectors
on track zero nearest the edge of
the disk. If there are any errors in
either of these two sectors, the rest
of the verify program cannot
operate and the program will report
the fact and stop. Assuming the
catalogue has loaded correctly, the
program will then report
The number of sectors on a disc
should be 400. A disk formatted for
eighty tracks will have 800 sectors
and will not work in the standard
Atom disk pack, though it is sti
possible to read the catalogue off
an eighty-track disk.
The program will then, for each
program saved on the disk, print:
• file name.
• start address in memory where
the file would be located to
• execution address of the file,
• length of the file in bytes,
• location of the first sector of the
file on the disk,
• number of sectors on the disk
occupied by the file.
A row of dots should be printed
below every file name. Each dot
represents a sector of the file that
has been verified. Any stars printed
indicate sectors that cannot be
loaded or verified. Any areas of the
disk not allocated to files will be
reported as blank and verified in
the same manner, in particular you
will normally find a large blank area
after the last file on the disk.
If you do not wish to verify the
whole disk, the escape key may be
used. However, as the screen is
disabled at certain points in the
program, control F should be used
after pressing the escape key to re-
enable the screen. The correct
sequence to escape is therefore
ESCAPE, control F, RETURN, the
error message can be ignored. The
result on the screen is a clear
visual indication of the size of files
and blank areas on the disk, and
corrupted sectors.
ACORN USER SEPTEMBER
37
ATOM EXTRA
Acornsoft's 20k BBC ROM conversion
module can be added to an Atom,
which will support thefull set of BBC-
type Basic commands. The syntax is
identical, so all programs that don't
rely on BBC hardware can be run on
the Atom.
The module is fitted in parallel with
Atom Basic and may be selected by a
switch or from the keyboard with
modifications. It consists of 1 6k Basic
ROM, a 4k operating system ROM
and an additional 2k RAM that can be
used by the Atom as well. A com-
prehensive manual is supplied
giving operating and fitting instructions.
The conversion board uses the
same 16k Basic ROM as the BBC
micro. The board includes a 4k MOS
ROM to provide the correct machine
environment on the Atom. The board
also includes logic to alter the memory
map so that RAM is available from
0000 upwards, and so that the 16k
Basic ROM can reside at 8000 to
C000.
The BBC-Basic time function is
implemented by means of interrupts,
generated by the Atom's 6522 timer
(which must therefore be fitted).
The BBC board is fitted by removing
four integrated circuits from the Atom
and inserting these in sockets on the
board. The board is then plugged
into the empty sockets on the Atom.
The BBC Basic board includes
16k Basic ROM, 4k MOS ROM,2kof
additional RAM. socketfor utility ROM,
socket for MOS extension ROM.
decoding logic.
The board can either be wired
permanently in BBC-type Basic
mode, or, with the addition of two
wires to the Atom keyboard, you can
select between Atom or BBC-type
Basic by pressing CIRL-BREAK or
SHIFT- BREAK respectively. Alter-
natively, the module can be fitted by
your dealer.
The commands MOVE, DRAW, and
PLOT are supported, with drawing of
lines or points, relative or absolute,
and drawing in white, black or inverted.
The facilities for area fill and dotted
lines are not supported.
The board allows users to type in
BBC programs, but cassettes
cannot be loaded. It costs £49.95. 1
L-.ll. 1*1'. I MP *»**
^ii W M Bfia ^o^^
BBC Basic board fitted inside the Atom
Memory map for conversion
Atom mode
Atom ROM
Optional DOS
Extension ROM
Atom ROM
I/O
Utility ROM
^\\\\\\\\\\\\\-^^
Graphics
RAM
RAM
FFFF
FOQO
EQQ0
D00Q
C000
B000
AOOO
9800
BBC-type mode
oQQO
1 000
6000
5800
-1000
3OQ0
?ooo
MOS ROM
Optional DOS
Extension ROM
Optional MOS
BBC
Basic
I/O
Utility ROM
Graphics
RAM
Optional
RAM
Odoo
0000
RAM
38
ACORN USER SEPTEMBER
Electronequip
(Authorised BBC and Acorn Dealer, stockists and repair centre
BBC1 BBC Micro Model A £260.00
BBC2 BBC Micro Model B £346.96
BBC21 Upgrade Mode! A to B £100.00
BBCxx Other Upgrades Phone for price
BBC32 1 4" Colour Monitor £250.00
BBC35 BBC Cassette Recorder £26.00
BBC36 Casette Lead DIN to Jack £4.00
BBC40 Single 5 25" Disc Drive £230.43
Epson Printer MX80T type 3 £325.00
Epson Printer MX80FT type 3 £345.00
Epson Printer MX! 00 type 3 £445.00
ATM1
ATM2
ATM3
ATM10
ATM11
ATM25
ATM 26
ATM53
BMC
BMC
Atom assembled 2Kram £140.00
Atom assembled 12Kram £160.00
Atom assembled 5Kram colour £158.00
Atom kit 2Kram £110.00
Atom kit 12Kram £130.00
New PAL Colour Encoder £38.00
New 1 8A Power Supply £8.40
Atom Cassette lead £2.00
1 2A Black/Green Monitor £79.00
1 2E Black/Green Monitor £99.00
Prices exc. VAT and inc. postage (except BBC micro's 2.00)
All items always in stock (even BBC's) — quick despatch
Upgrades include fitting and testing. Credit cards not accepted for BBC micro's
Electronequip BOB
128 West Street, Portchester (A27 opp. RUBY) Hants P016 9XE Tel: 0705-325354
ACORN PLUS
r NEW 100 PAGE
CATALOGUE ^
Control Universal stock Acorn, Rockwell, Cubit and fine peripherals. Send for our catalogue.
ACORN
STOCK
MORE-
STOCK
CUBIT
*<-
**-
Ring Control Universal on four telephone lines for technical advice and fast deliveries on all Acorn
products- Eurocards, systems. Atoms, all software, networks components, connectors, spares
- everything you need.
Control Universal also stock Rockwell Computers, EPSON and TEC printers, BMC and MICROVITEC
vdu displays. G.P.I. EPROM programmers and erasers, disks, stationery, memory and TTL chips.
The CUBIT range is made by Control Universal and includes single board computers with 4K RAM and
VIA i/o chip for 6502, 6802 and 6809 processors; CU-MEM memory card for eight 24 or 28 pin memory
chips, with on board battery back up for CMOS RAM; CUBIO 64/80 channel digital i/o card;
CUBAN eight bit analogue interface with 16 analog inputs, one analog output and 20 digital i/o channels;
CU-KEYascii keyboard.
'ATOM PLUS 17K RAM — £69
why 17k?
- to fill in the gap from hex 3COO to 3FFF with 1 K of
static RAM, and provide 16k of dynamic RAM from
3000 to to 7FFF. Uses 5v only devices, and fits in the
standard Atom case.
Standard Eurocard size and bus connector.
'CU-DRAM' 64K bytes DRAM - £99
For all Acorn and Control Universal systems. Each block
of 4k can be enabled or disabled to match the system.
Carries also a 4k/8k 28 pin socket for ROM or EPROM,
and can be software selected at board level to allow up to
1 6 boards in one system and hence a maximum of
1 Mbyte of RAM.
Standard Eurocard size and bus connector.
CONTROL UNIVERSAL LTD.
Unit 2, Andersons Court, Newnham Road, Cambridge
(0223) 358757
VISIT OUR
NEW SHOWROOM
ACORN USER SEPTEMBER
39
AfYiwygHTRTins tor
Bn]0«ATOtA
Printers
Selk sha GP100A
Epson MX80 F/T III
Printer lead f specify BBC or Atom)
Cassette
Sanyo cassette recorder with motor
control (compatible with BBC <Sf Atom)
Cassette lead 'specify BBC or Atom;
Monitors
;.■ >we IS" green screen monitor
Vldet lead for above i specify i ■ mputer)
Crofton Prince 13" hi- res green m nitor
Video lead for above 'specify computer
Microvitec 14" RGB o - ir monitor - as
recommended forBBCMicr
Power Supply-
March AP£M hl-spee P.S.U. for Atom
Consumables
Listing | aper for GP1O0, MX80 500 sheets
Continuous labels for same 1000 f r
C.12 data cassettes I
Books
30 Hour BASIC (BBC
Lei Your BBC Micro Teach You BASIC
Practical Programs for BBC 3? Atom MlCP e
letting Acquainted With Acorn Atom
Acorn Atom Magic Book
Atom Business
&84S.00*
£448.00*
484.98
£26.98*
&4.80
£91.98*
£7.98
£138.00*
£9.98
£309.38
£28.80-
: £4.78
£4.78
£4.78
£8.80
£6.48
£8.98
£7.98
£8.80
£6.98
•I felivery £2.50; ctherv.'tse 8op for orders under £13, over
£10 sent free. ALL PRICES INCLUDE VAT where appropriate.
Liverpool Computer Centre
14/16 Manchester Street, Liverpool, LI 6ER.
Access & Visa Accepted 081-236 2000
Run [BMC] type BASIC on your ATOM
then switch back to ATOM BASIC
Available now from Acornsoft, a 20k BBC ROM
conversion module which can be added inside an Atom.
It will support the full set of BBC - type BASIC
commands. The BASIC syntax is identical so all programs
that don't rely on the BBC hardware can be run on the
Atom without any modification.
The module is fitted in parallel with Atom BASIC and
may be selected by a switch or from the keyboard if
certain modifications are made. It consists of 16k BASIC
ROM, 4k operating system ROM and an additional 2k
RAM that can be used by the Atom as well.
Complete with manual
A comprehensive BBC - type BASIC manual is supplied
with every set giving full operating and fitting
instructions, alternatively the
module can be fitted by
your dealer.
The price is £49.95
including VAT.
If you don't have a dealer near
you just write to us with
with a cheque at the address
below, or credit card holders
holders can ring Cambridge
(0223) 316039 and order directly.
Dept AU 2, Acornsoft Ltd.,
4a Market Hill, CAMBRIDGE CB2 3NJ
THE ^ICORN SPECIALISTS
COMPUTER
ATOM & BBC MICROS
UPGRADES •ADDONS
• BOOKS
PERIPHERALS •SOFTWARE
EX-STOCK
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PROGRAM POWER
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[DOB
MAIN t-LJ L^J »^# AGENT FOR
WARRANTY REPAIRS & SERVICE
KINGSTON
Tinr
>NAL ARROWS |f| WO p5k" 8
I M FOLLOW DIRECTIONAL.
mom 23 ° Tolworth Rise South. Tdworth, Surbiton. Surrey'KT5 9NB
Wephone:01-337 4317 Telex:945966AIROAG
TYPEWRITER
CENTRES
For all your VIC requirements
- branches throughout the
MIDLANDS and BOURNEMOUTH
PET specialists
-COMMODORE appointed dealers
BIRMINGHAM
City Centre:
52 Bromsgrove Street
Edgbaston:
92 Dudley Road (opp. Hospital)
Erdington:
52 High Street (opp. Library)
Kings Heath:
46 High Street
Sutton Coldfield:
Knights House,
Gracechurch Centre
LEICESTER:
34-36 Rutland Street
WALSALL:
7 Leicester Street
WOLVERHAMPTON:
68 Worcester Street
COVENTRY:
128 Far Gosford Street
BOURNEMOUTH:
75 Seamoor Road, Westbourne
021 622 5385
021455 9111
021 382 0185
021 444 7349
021 255 6789
0533 538745
92 27589
90 27627
0203 28799
0202 766997
40
ACORN USER SEPTEMBER
ULA DESIGN
The chip that made
a name for itself
i
n designing an Acorn computer
we consider the system both from
hardware and software points of
view. But between these two is a
grey area where functions can be
implemented by either. Often the
specification of a computer can be
enhanced by implementing complex
low level software functions in
hardware. To do this we need to
design hardware rapidly and
cheaply.
This can be done if we design
chips specifically for the application,
as off-the-shelf components often
provide features we do not require.
There are exceptions: chips such
as microprocessors and memories
are standard parts which can be
manufactured in volume to cut
costs. Specially designed chips
can also be used to 'mop up' the
board and keep the number of
components to a minimum.
There are many ways of
designing and manufacturing a
semiconductor chip. At one
extreme there is the fully custom
approach where all steps in the
manufacturing process are specified
by the designer. Each transistor,
resistor and chip component is of
the right size and type to perform
its function. At the other end,
programmable logic arrays (PLAs)
have been designed which perform
complex combinatorial functions
but have no memory, and so can
only be used to implement
restricted system functions.
Between these there are
uncomitted logic arrays (ULAs).
These are chips where most of the
design work is already done and
components have predetermined
There's no smoke without fire
and although computer
magazines make little of the
issue (right), Sinclair does
seem to have been hit by the
same problem that delayed
the BBC micros - faulty ULAs.
But how can one chip cause
such a fuss? Acorn director
Andy Hopper explains the
tricky aspects of uncommitted
logic arrays in system design
values and sizes. Furthermore, these
basic building blocks are in fixed
places on the chip. Normally this is
done on a grid with components
grouped into cells, which are then
arranged in rows across the chip.
To commit the chip, or customise it
to a design, the designer has to
specify how these building blocks
are connected. Normally this is
done by a small number of easy
manufacturing steps so the chips
can be made cheaply.
I
.here are many ULAs designed in
both bipolar and MOS technologies
and in sizes ranging from 100 to
8000 gates. Customisation is
carried out by depositing either a
single or double interconnecting
layer of metal on the surface of the
chip. In some ULAs, the metal
connects resistors and transistors
which are used to form gates, in
other systems the gates have
already been manufactured and the
customising is done at a higher
level.
Depending on the application
the ULA works at a speed at which
it can communicate with the
neighbouring logic. The fastest
ULAs have switching speeds of
less than one nanosecond per
gate. Then there are systems which
switch at tens or hundreds of
nanoseconds per gate, but
consume less power. Hence a
larger number of gates can be
houses in one package without the
need for special cooling.
To make ULAs versatile it is
ACORN USER SEPTEMBER
41
ULA DESIGN
possible to specify the voltages on
the pins used to communicate with
other chips. Thus it is easy to mix
MOS, TTL and ECL logic or use any
other system. This is normally
possible because around the
outside of the ULA there are
peripheral cells which contain
components used to implement pin
driving functions. In some cases it
may be possible to perform simple
analoguefunctions in this way.
T
o design a ULA it is necessary
to know the rules for implementing
logical functions. The ULA concept
restricts the way components can
be connected but this has the
advantage that it prevents mistakes.
The rules are simple and specify
the maximum fan-in and fan-out of
a gate and may prohibit some
unusual forms of asynchronous
logic. To design the chip it is also
important to take into account the
propagation delay of each gate and
how this varies with the way it is
connected to others, with
termperature and with production
tolerances.
Once equipped with the design
rules it is possible to specify how
ULAs are to be committed. This can
be done either by designing in
some other logic system - such as
TTL - and converting to the chip
design, or by designing directly in
the logic system of the ULA. The
former approach has the advantage
that it is possible to build an
emulation easily. The latter allows
gates to be used only as required
and it is possible to take advantage
of ULA features to design systems
which would otherwise be
impossible with discrete logic.
There is an example of this kind of
flexibility in the BBC machine's
video processor.
I
n this we have used a palette
memory which provides some of
the sophisticated graphics features.
The memory is dual-ported so it
can be addressed in two ways, one
for up-dating and the other for
reading contents. This would take
many more components if it were
done externally in discrete logic.
When the logic design is
complete the likelihood of
ULA casing hides 8000 gates
successfully computing the physical
interconnection structure of the
ULA is estimated. To do this, the
gates in the system are counted.
Clearly this must be less than the
total number of gates available for
connection. However, if the design
is complex, it may be difficult to use
each gate without blocking-off or
encircling others. Thus it may take
great skill to use more than three-
quarters of the available components.
However, as the chip price is not
very dependent on the number of
components used, there is always
pressure to use as many gates as
'Some faults
only appear
in extreme
conditions'
possible. All Acorn ULAs have used
95% or more of the available
components.
When designing the ULA it may
be possible to implement analogue
as well as digital functions, but this
is only possible with ULA systems
where individual transistors and
resistors are available for
interconnection. An analogue
circuit on the BBC machine serial
processor can approximate a sine
wave used for storing data on
cassettes. This interface performs
well because the ULA allows a high
quality approximation to be
provided cheaply.
Although ULAs can be designed
using hand techniques, as the
number of gates increases software
tools have to be provided. These
fall into two categories: simulators
which predict the behaviour of the
chip before manufacture and
layout, and layout and verification
programs which take the simulated
design and implement it on a ULA.
Therefore a complex design is
begun by simulating the logic. To
do this the design is specified
using either graphical input or a
se. Once the design
has been described it can be
simulated by providing input
waveforms. The outputs are then
checked until the design is
satisfactory. To convert this to a
physical chip The gates are placed
on the surface of the ULA (or
allocated to uncommitted com-
ponents) and then connected
together.
A
Ithough programs exist to do
this automatically, complex designs
require manual intervention. Because
the simulator only uses assumptions
about the location of gates and
because hand intervention may
have introduced errors, it is crucial
to be able to simulate the chip
using the physical implementation
as the model. Only once this has
been done and the results are
satisfactory is the information
passed to a manufacturer who
makes the chips. If the tools are of
high quality the chip will perform
exactly as the simulator predicts
and work first time.
M
anufacturing steps are fairly
simple - but they take time. If a
fault is found it can take months for
it to be corrected. In particular, if
the design assumes everything will
work and does not provide facilities
for tracing faults, debugging may
be a severe problem. Also it is easy
to try to use more components than
can be utilised on a chip. The
design may work with small
variations in production tolerances
but may fail if these change
substantially. Some faults may only
become apparent at extreme
operating conditions. Everybody
has heard about the BBC machine
ULA problem. This was caused by
a fault which did not show in
samples but was present in later
chips. Although it was quickly
traced and corrected, the delay in
production almost made ULAs a
household word. $
42
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ACORN USER SEPTEMBER
43
MODE 7
• , *
:': : S£
- *
3
> I 1 * « t
—
§23
U*
3
:::r
. - — 1 I * * —
■4-i *^rf
, » , » -
. lit.
r «-
« * ♦ .
i
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* ' * 1 1**4'
^D:~
■ I
; * 1 ) *-—-<—
* * I lata v * i *
1
SDH
- - . -1 -
• * 4 ... i I
::::D : n
-*—— — -» • -f * — J
r * * * * I * * ^nP
t:ttt:;S
nu-r'-l
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If
FTi n
j!;.:..—!
.
: l^
rn
::rH
* — » - -
h- * 1
i**4*
Spss
3fe*i
Paul Carpenter and Graham Field
of the ITMA project explain how they write
programs using teletext graphics
onverting programs to run on the
BBC Machines has presented the
ITMA project with a major problem.
Software has been written for the
Research Machine, 380Z micro-
computer and although programs
convert relatively easily, there is not
enough memory on the model A to
use any of the graphics modes and
have the program in memory. Even
using the model B has proved
impossible with some longer
programs. But the flexible graphics of
the BBC machine provided an
answer - write programs using
Mode 7 in teletext graphics
characters (see below).
Although mode 7 is not precise
enough for accurate scientific
representation, or measurement it
can provide perfectly adequate
displays for educational programs
when used with care.
The teletext character set consists
of two sequences, which we will call
Pirates. . . just one of the
programs ITMA has converted to
run in BBC mode 7
C3,4>:GO NORTH EAST
TRY NO. 2
III
lilt
„ "' iiiL
IL
n
1
III
X IS FRO
Y IS «
I'l'
FIND THE TREASURE?
Hi ii ; i ij""i <tJ
__
LEFT
TO ;
THE TREASURE »
44
ACORN USER SEPTEMBER
MODE 7
the alphabetic sequence and the
graphics sequence. The former
consists of standard ASC1 1
characters 32-127, display control
codes 128-159, and the ASCII
characters 32 - 1 27 repeated from
160-255. The latter has the same
control characters from 1-31, the
same display control characters from
128 - 159 and the upper-case letters
together with a few other characters
repeated twice between 64-95 and
192-223. The graphics themselves
consist of six small squares forming a
3x2 grid for which the code may be
calculated from the scheme in
figure 1, to which should be added
an offset of 1 60.
he alphabetic sequence is
selected by writing an alpha control
character, and the graphics
sequence by writing a graphic control
character (see figure 2) on the current
line to the left of the character to be
displayed.
Two things must be remembered
about the display control characters.
Each effects the remainder of the line
it is on (until changed by another
control character) and each occupies
one character position on the screen.
Thus:
PRINT TAB (5); CHRS136;
CHR$132;"**'
will display a flashing (CHR$136),
blue (CHR$132), star at the seventh
position on the line.
To change background, first
decide, and set, a colour, change to a
new background (which will be in that
colour) and then choose and set a
character colour. Thus:
PRINT CHR$1 31 ;CHR$1 57;CHR$1 48;
will display, on the remainder of the
line, blue graphics characters
(CHR$148) on a yellow (CHR$131
background (CHR$1 57).
o view the mode 7 graphic
character set, run the following
program:
10 MODE 7
20 FORJ=32T0 126
30 PRINT J:CHR$151,CHR$I
40Z=INKEY(20)
50 NEXT
60 FOR J=1 60 TO 254
70 PRINT J:CHR$1 51 ,CHR$I
80 Z=INKEY(20)
90 NEXT
BIGALF. . . an introduction to the
alphabet which uses screen
colour techniques described
below
Note that CHR$151 on lines 30 and
70 defines white graphics. For a
different colour, change the 151 to
the appropriate code, for example
1 46 changes the colour to green. The
following example shows how to
colour the whole screen yellow and
print the word FRED in red, double
height characters:
10 MODE 7
20 REM COLOUR SCREEN
30 FORJ=0TO24
40 PRINT CHR$147,CHR$1 57;
CHR$129
50 N EXT
60 REM PRINT DOUBLE HEIGHT
70 PRINT TAB (20,1 0);CHR$1 41;
"FRED"
80 PRINT TAB (20,1 1 );CHR$1 41 ;
"FRED"
90 END
This facility is used in the program
... 46 ►
To produce
character
>
use
1+8+16+160
1
2
4
8
16
64
Display
control characters
129 Alpha red
130 Alpha green
131 Alpha yellow
132 Alpha blue
133 Alpha magenta
134 Alpha cyan
135 Alpha white
136 Flash
1 37 Steady
140 Normal height
141 Double height
145 Graphic red
146 Graphic green
147 Graphic yellow
148 Graphic blue
149 Graphic magenta
150 Graphic cyan
151 Graphic white
152 Conceal display
153 Continuous
graphics
1 54 Separated
graphics
1 56 Black background
1 57 New background
Figure 1 . Six squares make up a
graphics grid used to build up
characters
Figure 2. The graphics sequence
is controlled by these characters,
each of which effects the
remainder of the line it is on,
until changed by another
character
ACORN USER SEPTEMBER
45
MODE 7
Wordworm. . . spelling program
BIGALF which was designed as an
introduction to the alphabet for young
children.
outines to plot individual squares
are shown in Figure 3. To use them,
clear the screen and put the
appropriate graphics controls down
the left-hand side of the screen. Do
any display of (upper-case)
characters using PRINT TAB (x,y);
where y is always less than 24. Do
not allow the screen to scroll.
We have found the Basic
interpreter fast enought to cope with
moving displays using these routines,
as in our spelling program,
Wordworm above in which a 'worm'
is steered by the user to eat the
letters of a word.
The ITMA Project - Investigations on
Teaching using Microcomputers as an Aid
- provides a back-up for teachers. Details
from; The Secretary, ITMA Project, College
of St Mark and St John, Derriford Road,
Plymouth, Devon PL6 8BH. *
Figure 3. Listing to plot individual
squares
10
20
30
40
SO
60
100
110
120
130
500
510
520
530
540
550
560
580
590
595
600
alO
620
630
6*0
650
660
670
680
690
695
700
710
720
730
740
750
GRAPHICS ROUTINES
across rn* scr--r
doi'in 1 h* screen
REM
REM
REM X •*■ runs from to 7*
REM i'l runs from l- to 69
FEM
REM Include this funct-or. in al i proarams
DEF FN!nasl<(AX,D*)*4*;DX*2 A * - 32*<AX*D**2>
REM
REM* Test location X'X.V*« Return ASCII code if le*
REM if empty ? 1 if s*t . 2 for a conirut charged
DEF FNtest<X*.YX>
LOCAL Mt,i)% t flilt,til%,P%
PRQCpicKOUT(Xl,yj '
lF(F/.>63 AND R'/<96> OR (P3t>191 AND Pfc<224i THEN 1
IF ■>*■/ '32'' OR (Pl>126 AND P*< 160) THEN P«-2*GOT0
IF PX<127 THEN PX-PX-32 ELSE P**Ptf-16Q
P4— <<PY AND FNmagki Al/ ,D1*J > > 0)
-P/
REM
REM Allocate crarscrer oosition ic coordinates ,<i
DEF PROCpicKout<XX,YX)
a; - x/. DlV 2: Al/ = «/ MUD 2
D* * V7 L"1V 3: DlV. = Y* MOD 3
i er
tr* *
BO
5fiQ
. v/.,
PY = "MHIMEH + D*#4Q +
IF(PX)31 AND PX<64> OR
ENDPROC
REM
a;.>
(PS S>
AND P'/<127> THEN PX»P*+i2fi
REM
REM
REM
REM
DEF
Plot
CX>1
C/=i
cz.=o
aT X*. Y/-
A graphics
characer or l*i*trr
A BMa I 1 square in
A stiia i l 5 quare* in
PRQCplot(XX,YX,CrX)
PROCpicKout iXi,yO
IF CA>L THEN P»=CX;GQTQ740
PX=PX-IP* AND FNNidSMAlJt.DlK) )
PR INT TAB t A/- , D7> ) ; CHRS < PX )
ENPPROC
ih* foreground col
rhe bdcKoround col
our
our
CSt*FNoiasK<AlS ■01/ j
46
ACORN USER SEPTEMBER
Addison-Wesley Computing
A series of quality,
reasonably-priced paperbacks
created to meet
the demands of the
microcomputer revolution
PASCAL FROM BASIC
Peter J Brown, University of Kent
If you're fluent in BASIC and want to go on to PASCAL
without starting from scratch again, this is the book for
you. Peter Brown explains the development, advantages,
and disadvantages of Pascal, illustrating each new idea
with an example. He calls it 'a computing book you can
read in bed'.
1 92 pages fully illustrated £5.95 paper
BASIC AND THE PERSONAL COMPUTER
Thomas A Dwyer and Margot Critchfield
An easy-to-follow introduction to programming in BASIC
and extended BASIC for personal computer applications,
this book illustrates the great diversity of applications
possible on a microcomputer. It is an ideal self-instruction
manual for the new user.
438 pages fully illustrated £9.95 paper
REAL TIME PROGRAMMING - Neglected Topics
Caxton C Foster
A practical, applied book for experienced programmers.
REALTIME PROGRAMMING provides an original
approach to acquiring the skills needed to connect
microcomputers to other computer systems and to
access their programs.
224 pages fully illustrated £6.95 paper
THE LITTLE BOOK OF BASIC STYLE: How to Write a
Program You Can Read
John M Nevison
Anyone with two hours' programming experience in
BASIC can use this book to improve their programming
style. It gives nineteen simple rules of style which, once
mastered, will reduce the time and practice needed to
write better programs.
1 60 pages fully illustrated £4.95 paper
Computers in Education
A PRACTICAL GUIDE TO COMPUTERS IN
EDUCATION
Peter Coburn, Peter Kelman, Nancy Roberts, Thomas
Snyder, Daniel Watt, and Cheryl Weiner
This concise American book will help teachers in Britain
take full advantage of the educational opportunities
offered by microcomputers. Spanning all ages, abilities,
and subject areas, it is filled with practical tips,
recommendations, resources, and actual classroom
applications.
1 92 pages fully illustrated £6.00 paper
Graphics
FUNDAMENTALS OF INTERACTIVE COMPUTER
GRAPHICS
James D Foley and Andries van Dam
This comprehensive volume is indispensable for anyone
seriously involved with computer graphics. With over 500
illustrations, many in full colour, it covers every aspect of
creative graphics- hardware, software, data structure,
mathematical manipulation, user interface, and
fundamental implementation algorithms.
960 pages fully illustrated £1 5.95 hard
Artificial Intelligence
LISP
Patrick H Winston and Berthold K P Horn
This lucid account demonstrates how symbol
manipulation is used in practice. Case studies from many
different areas of artificial intelligence illustrate the basic
concepts and provide the information needed to go on to
further study.
430 pages fully illustrated £7.95 paper
Networks
THE CAMBRIDGE DISTRIBUTED COMPUTING
SYSTEM
R M Needham and A J Herbert, Cambridge University
Computer Laboratory
For those who already have some knowledge of logic and
computing system design, this book provides a complete
description of one complete network system -the
Cambridge Ring. The authors discuss the main design
issues, functions and applications.
286 pages fully illustrated £8.50 paper
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ACORN USER SEPTEMBER
47
TttClfRtfOlE
imuwmmxiP
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BOOKS
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Practical Programs for the BBC Computer and
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Getting Acquainted with your Acorn Atom . £7.95
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We stock the full range of ATOM and BBC Micro MICRO POWER Ltd.,
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48
ACORN USER SEPTEMBER
Part 2
by John Shaw
and Anthony Ferguson ofMEDC, Paisley College
f unctions can easily be driven from
an assembly language program. This
follows from the design of the BBC's
design of the BBC's display
software which is 'code driven' and
aimed at an intended future role of
the machine - namely a
sophisticated graphics terminal to
a second language processor,
6502, Z80 or a 16-bit option, with
its own memory.
The varied nature of graphics
programs makes it difficult to
standardise an approach to how
VDU commands might readily be
translated to a series of assembly
language statements.
As each command is accurately
defined by a series of data items,
one possible way is to use a
subroutine to send the series of
data items to the machine
operating system. For example:
VDU 25,0,0,0,0
is accurately defined by the data
series
5,25,0,0,0,0
where the first number, 5,
indicates the number of separate
data items that follow and are to
be sent to the machine operating
system via subroutine OSASCI.
/he subroutine in figure 1 will
send any such series of data items
to the machine operating system.
It uses the first number in the
series to determine how many
times it must call the subroutine
OSASCI and send a byte of data.
A pair of page memory
locations are used as a pointer to
the appropriate data items to be
output and the subroutine is called
successively for each data item to
be sent. The VDU command is
stored as a series of parameters to
be sent to the machine operating
system via the subroutine and any
change in the variables (e.g. x, y
data pairs) to be sent can be made
to the appropriate values in the
data series. Two or more
commands that regularly go
together can be made into
combined data series for faster
execution.
This technique is illustrated in
figure 2, a new version of the
earlier somewhat lengthy program
(Acorn User, July). This is only one
possible approach to adopt and is
not universally suitable for all
assembly language programs.
Since changing the graphics
colour is always followed by
homing the cursor these
commands have been combined
Figure 1
100
110
120
125
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
REM assembl
OSASCI=&FFE
PNT=&70
DIM A 100
FOR PASS=0
P% = A
REM subrout
REM data by
REM on entr
REM require
[OPT PASS
y language graphics
3
TO 3 STEP 3
ine to send string
tes as VDU command
y PNT set to start
d command string
of
of
.SEND
.NBYTE
]
NEXT
END
LDY
LDA
STA
INY
LDA
JSR
CPY
BNE
RTS
PASS
#0 ;Y counts bytes
(PNT) , Y ;save string
PNT+2 ;length here
(PNT),Y
OSASCI
PNT+2
NBYTE
- ; s e n d next
;byte
; finished?
ACORN USER SEPTEMBER
49
GRAPHIC
into a single series of bytes.
Unfortunately, the BBC assembler
does not support a define byte
statement and the data values
have been placed into RAM from
Basic at CCHC. Since CCHC+3
always contains the byte that
represents the foreground graphics
colour, its value in the data series
is changed from within the
program.
ghe command to draw the line
horizontally across the screen is
also a series comprising two
commands that always go
together. This series has been
placed into RAM at DLIN. After
assembly they can be run using
the CALL command.
All versions of this program,
including the Basic one, will
produce far more interesting
screen effects if, instead of
changing the screen colour, the
colour relationship parameter is
changed.
In the Basic program this is the
first parameter in the GCOL
statement. The changes required
are:
105 FOR Rel=0TO 255
120 GCOL Rel, Colour
190 NEXT Rel
In the final assembly language
program changing lines 450 and
460 to
450 INC CCHC+2 Inc colour
relationship
460 LDA CCHC+2
The unique design of the display
software on the BBC microcom-
puter gives the programmer easy
access to all the graphics
functions from a machine code
program. Since Basic and machine
code programs use the same
graphics software, the latter does
not necessarily lead to any
significant speed advantage.
However, machine code pro-
grams should prove useful in
allowing the programmer to build
up a collection of routines that lie
outside the Basic text area, loaded
directly from tape or housed within
the machine in EPROM. Such a
library of routines would prove
useful in expanding the graphics.
For example, circle or arc drawing
routines could be written that
would be available for use from
Basic or any other high level
language option as required. $
Figure 2
100
L 10
120
130
140
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
510
520
530
540
550
560
570
580
590
600
610
620
630
640
650
660
670
680
,NC0L
REM assembl
MODE 5
REM
REM placing
DIM DLIN 20
REM draw li
FOR J = DLI
READ BYTE
? J=BYTE
NEXT J
DATA 12,25,
CCHC=DLIN+1
FOR J = CCH
READ BYTE
?J=BYTE
NEXT J
DATA 9,18,0
OSASCI=&FFE
POINT=&70:
FOR PASS=0
P%=CCHC+10
OPT PASS
LDA
STA
LDA
STA
JSR
LDX
LDA
STA
LDA
STA
JSR
DEX
BNE
INC
LDA
CMP
BNE
RTS
]
REM subrout
REM data by
REM On entr
REM requi re
REM Note -
OPT PASS
y language graphics
the command data into RAM
nes command
N TO DLIN+1
data
1,0,5,4,0,25,1,0,&FB,4,0
3
C TO CCHC+9
,0,25,4,0,0
3
REM page
TO 3 STEP 3
,0,0
locat ion
.NLIN
//CCHC MOD
POINT
//CCHC DIV
P0INT+1
SEND
#128
//DLIN MOD
POINT
//DLIN DIV
POINT+1
SEND
NLIN
CCHC+3
CCHC+3
//16
NCOL
56 ;set pointer to
;CCHC data
56
56 ; set pointer to
; lines data
56
SEND
.NBYTE
LDY
LDA(
STA
INY
LDA
JSR
CPY
BNE
RTS
ine to send
tes as VDU
y POINT is
d command s
corrupts Y
#0 ;
POINT), Y ;
POINT+2 ;
(POINT) , Y
OSASCI
POINT+2
NBYTE
; dec line count
; ano t he r line?
; i nc co lour
; finished?
jreturn to BASIC
string of
comma nd .
set to start of
tring
reg
set byte count
save string
Length he re
send next
byte
f ini shed ?
]
NEXT
END
PASS
50
ACORN USER SEPTEMBER
I»
\h
in
D
% •
DO
r r
Flashing 'Power
Pills' -after snapper
has eaten them the
ghosts turn blue.
Snapper makes After the ghost has The ghosts eyes
eating noises as he been snapped' their always look in the
snaps the ghosts, dots eyes return to the caw. direction they ace
and fruit. going.
Blue ghost ready Fruits increase
for eating. H not eaten value with higher
quickly they flash and scores*
revert back
Bonus points
awarded for eat i ng fru rt ■
4»\ 8
.DID
W
'WWII II
(flit
!il||l|l!l|lllll|lll!ll!lllltl
i : hi
lllllllllllllllllllllltlllllllllllllllHllHlllllllltlllHIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIMIIIIIIIHIIIMIIIIII.
■
iMtiiiiiuimiiiiitmmiiiii iiiiiiihiihii i *»|
\tl
ii M-ii
il|l|IHIMIHII(lllll|IHIt1IHI|i|
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■ . ■ ■■ I. nililtlltHlHIlHItllltlltllUlillHllllllNIHIHltHIHIIlHtlllHIilHIlP
'""UMllMffl
.lllllllt'l:.
rimmnriiirimmnmmnm
"'ii mw— — ihiiiiihi .
— ;:;„
Snapper-the new addictive arcade-style game for the BBC micro from Acornsoft.
Snapper's food is fruit and he must eat to stay alive. Ghoulish ghosts try to gobble him
up and he can't fight back until he has found and eaten a power pill.
A total of 1,000 points is the minimum to rank among the top eight players on the
high-score table- but the highest known score is 127,000!
Snapper has amazing eight colour graphics
with full sound effects and a high score ladder.
ft* full detail! oJ this and other ctciting games fof the
BBC Microcomputer S^Uem rmg 01 930 1614 of wnte to
w 4_ / . \S \~f \~f » ***** m*u«j*H|JWHJ ofMrm rm% UJ-»U lOl* Of WTO K*.
Acornsoft Ltd 4a Market Hill CAMBRIDGE CB2 3NJ.
ACORN USER SEPTEMBER
51
SCHOOLS
Getting analogue data onto the screen with a BBC model B is easy.
Ian Carpenter, a Cambridge science and microtechnology inspector
shows you how. If you haven't got the upgraded model,
don't worry- getting from AtoB is as easy as. . .
ANALOGUE IN
M
icrocomputers are digital devices,
they live in a world of 'on' and "off
or Os and 1 s. But the world around
us is not so black and white, so to
connect the real world to a micro
you need an analogue *o digital
converter (ADC). The model B is
fitted with a converter available
through the 'analogue in*
connector. Don't despair if you only
have a model A; about £1 and 1 5
minutes will sort that out.
BBC Basic fetches the
Analogue-Digital VALue from the
ADC with the instruction ADVAL (1).
There are four channels on the
ADC chip so the number in
brackets just selects which
channel.
Type this into your computer:
P. ADVAL (2)
Model A owners can easily add
on the 'analogue in' facility. A
74LS00N chip fits in socket
IC77, a D7002C ADC chip fits
in socket IC73 leaving 10
minutes to solder a right angle
15 way 'Dee' socket onto the
main board using the holes
provided. If you are not happy
doing this job yourself, have a
word with your Acorn dealer.
you will get a number, about 60,000
returned. Try it again, you should
get another number at about
60,000. As we haven't connected
anything to the 'analogue in'
connector we are getting random
numbers returned through ADVAL
Voltages of from to 1 .8 volt fed
into the connector produce
numbers in the range to 65,520
(see User Guide for why). The
easiest way of feeding this voltage
in is to use a variable resistor or
potentiometer connected beween
to 1 .8. The computer gives us and
1.8 on the 'analogue in 1 connector
on pins 5 and 11 respectively and
we can feed back our voltage on
pin 1 5. (Note that Adval (1) refers to
CH0, ADVAL(2) to CH1 etc on the
diagram on page 223 of the
provisional guide, note also error
number 2,756! (Pin 14 is not CH1 it
is VREF.)
Let's look at a program using
ADVAL Program 1 is called 'paint
the adder' and draws a snake on
the screen - you have to paint the
stripes on his back using a
potentiometer as a paint brush.
a
lOkn
Figure 1. Wiring up potentiometer
lOk
pin ll(l-8v)
pinl5(CHO)
pin5(Ov)
Figure 2. Inside the device
5
oooooooo
oooooo
15
II
Figure 3. 'Analogue in' socket on
model B
Pendulum recording . . . same period,
but different amplitude
52
ACORN USER SEPTEMBER
SCHOOLS
Lines 1 and 20 clear the screen
and select a graphics mode with
text and graphics combined. Line
30 determines the x co-ordinate of
the snakes head whilst line 40
determines the y co-ordinate.
PROCBOX is a procedure defined
in lines 150 to 160 which fills in a
box on the screen at co-ordinates
x,y.
JLjine 70 takes the value of ADVAL
(1) and divides by 65 to make the
number returned to be in the range
to 1000, so it fits on the graphics
screen. Line 80 uses the value of V
to print '>' on the back of the
snake so our simple voltage divider
potentiometer can move the arrow
up and down the screen to leave
the '>' on the adder's back (with
practice!). Line 90 slows the snake
down - if you get good you can
reduce the 20 to a smaller number
to suit your ability. Line 140 allows
you to repeat the game by pressing
the space bar.
The 'paint brush' or games
paddle should be made from a
10kn potentiometer as shown in
figures 1-3. The 1 Okn potentiometer
should be linear' but a 'log' type
could be more fun.
Any aspiring (or perspiring!) O-
Level physics student could have a
great deal of fun rearranging the
potentiometer above with a piece of
string and a small weight to get the
arrows painted automatically on the
snake's back. Fun maybe, but it
does have a serious side because
many of the measurements made in
school laboratories could be fed
into the BBC micro for processing
and display.
Cambridgeshire Educational Com-
puting has produced programs
which allow pH, voltages, current,
light level, wind speed, temperature,
weight, mass and so on to be
displayed in large digits, on an
analogue scale or as a graph with
respect to time. Automatic weather
stations can be set up recording
say temperature, sunshine, wind-
speed and wind directions over a
time span of a week or, as shown
on the left, a recording over 20
seconds of the swing of a simple
pendulum showing that the period
is the same even though the
Britain. . . as seen on the screen
via a graphics tablet
lOMODE 5
20VDU5
30F0R X=0 TO 1100 STEP
20
40Y=450+250*C0S (X/90)
50PR0CBQX
60V0U26
70 V= ADVAL ( 1 ) /65
BOMOVE X , V : BCOL 1,2: PR I NT " > "
90Z=INKEY<20)
1 CONE XT
iiovDUi?,3,a,o,o,o
120S0UND 0,-15,4,30
130M0VE X+35, Y+50: GCOLO,
,3:PRINT"<"
140REPEAT UNTIL GET*=" '
' : GOTO
10
150DEF PROCBOX
160VDU24, X; Y; X+70; Y+70;
170GC0L1, 129: CLG
180ENDPR0C
Program 1 . Draws snake on screen ready for colouring
amplitude is significantly different.
Exponential decay of voltage
across a capacitor can be
displayed just as easily as a
cooling curve. These areas will
revolutionise science
over the next few
manufacturers beware!
Another interesting
using the 'analogue in' connector is
the use of a cheap graphics tablet
costing about £60 (one tenth the
cost of any conventional tablet).
equipment
years -
possibility
The software developed for
graphics tablets allows pictures to
be rotated and distorted to your
heart's content.
With a micro as good as the
BBC machine we are in for some
exiting times ahead.
Further details of software and
hardware can be gained (sae
please) from Cambridgeshire
Educational Computing, Resource
and Technology Centre, Back Hill,
Ely, Cambs. +
ACORN USER SEPTEMBER
53
SCHOOLS
TEACHING TEACHERS
R
nmary teachers in their
thousands are now showing an
active interest in computing, and
the advent of the BBC micro is
expected to swell their numbers still
further. We have the beginnings of
computer studies (learning about
computers) and computer-aided
learning (learning with computers)
two areas which often overlap.
Teachers are learning how
computers handle information in
the world outside school, and
discovering how computing could
be used to help children handle
information.
No one can claim to have all the
answers about computing and
primary education, but anyone with
initiative, a microcomputer and an
interest in education is well
equipped to join the pioneers.
A
.1 first, teachers looked to a
computer for help with work they
were already doing. Many
programs of the 'drill and practice'
variety were written, which children
find more attractive on a computer
than with pencil and paper.
However, despite the claims,
these programs do not teach,
although they can test or practice
what children have already learnt.
Far more exciting are programs
that aim to extend learning. These
may look more like play than work,
but they offer opportunities for
children to discuss ideas, think, try
things out and learn from mistakes.
Computer awareness and confi-
dence is something children can
gain once a micro comes into a
primary school, no matter what
programs are on it. Children can
see for themselves that computers
are fast and interactive, and that
information flows between the user
and the computer. They develop a
casual approach to the technology
that is the envy of many adults.
In many schools this is taken
further. At any age there is a certain
satisfaction to be gained from
understanding a program, knowing
what the computer must do, and
then imputting some information
that will force it to make a fool of
itself, or will outwit the programmer.
Such experiences can help
children develop a healthy
Pam Tiddy reviews the
problems facing teachers
who want to use micros
relationship with the technology,
and prove computers do not always
know the answers, and are not
better than people at 'getting things
right'.
c
hildren can be taught to program
from an early age - though
arguments rage as to whether they
should do so. But the intention is
not to turn everyone into
programmers, it just reflects the fact
that computers, like written words,
are important in our lives.
Learning to use a microcomputer
can be exasperating as well as
exhilarating, but help is available
from BBC micro user groups such
as MAPE, the Shell Centre for
Mathematical Education at Notting-
ham University, and the ITMA
Project at Plymouth.
Expertise and equipment is
spreading quickly beyond the inner
circle of committed enthusiasts.
Now computer users can hope to
be guided safely past the blind
alleys which have dogged early
developments in this area. $
EYES down! Mrs Thatcher
studies some positive results of
her micros for education
scheme at South Downs College
near Havant. The school has
launched a four-year microelec-
tronics programme supported by
local industry and Hampshire
County Council.
Help is at hand if you're stuck
Training courses are springing
up everywhere, but many
teachers have difficulty applying
their new-found knowledge when
they return to their own schools.
The ITMA Project (Investi-
gations on Teaching with Micros
as an Aid) and the Shell Centre
for Mathematical Education are
evaluating three types of training
course. Each gives a pair of
teachers a BBC micro, software,
evaluation material and six
workshop sessions. The difference
is in the level of support given
with the workshops. A school
with full support has the benefit
of a personal tutor with each
session. Medium back-up means
that the two teachers pack up
their computer and join others
for a workshop with a tutor.
Minimum support means no
tutor is provided with the
workshops. The results are not
yet available, but we'll let you
know.
Details of these courses are
available from Mrs. Rosemary
Fraser, ITMA Project, College of
St Mark and St John, Plymouth
PL6 8BH, or from Professor
Hugh Burkhardt, Shell Centre for
Mathematical Education at
Nottingham University.
A user group for teachers - and
parents - is MAPE (Micros and
Primary Ecducation), which was
formally launched in January.
Call for help to: Barry Holmes, St
Helens Primary School, Bluntis-
ham, Cambridgeshire (sae
appreciated). $
54
ACORN USER SEPTEMBER
INDEPENDENT NATIONAL USER
GROUP FOR THE BBC MICRO
DEVOTED EXCLUSIVELY
TO THE BBC
MICROCOMPUTER
REGISTERED REFERRAL CENTRE
FOR THE BBC PROJECT
ITT
FOR
THE
IU
CURRENT MEMBERSHIP
EXCEEDS 6000
BRITAIN'S LARGEST SELLING SINGLE-MICRO USER GROUP
BEEBUG Not only bring you 10 Magazines a year (now
36 concentrated pages) but provides two other
invaluable services:
A MEMBERS SOFTWARE LIBRARY and an
EXTENSIVE DISCOUNT SCHEME on products for the
BBC micro.
MEMBERS SOFTWARE LIBRARY
A growing range of software available to members at around £3.00 -
£3.50 per cassette eg
GAMES 1: STARFIRE (32k) Starwars type game with
excellent scjnd and graphics.
GAMES 2: MOON LANDER (16k) 3D NOUGHTS &
CROSSES (32k)
GAMES 3: SHAPE MATCH (16k) RAT SPLAT (16k)
MINDBENDFR (16k)
GAMES 4: MAGIC EEL (32k) MAN HOLE (32k)
UTILITIES 1 DISASSEMBLER (16k) REDEFINE
(16k) (Create your own graphics characters)
MINI TEXT EDITOR (32k)
APPLICATIONS 1 SUPER PLOT (32k)
Note: This software is only available to members ailhese prices. For further
details of our software library, and how to order cassetes. JOIN BEEBUG.
Membership: Send SAE for information or; Make cheque to BEEBUG and send to:
6 months - £4.90 Send £1 .00 and A4 SAE for sample. BEEBUG, Dept. 1 3, 374 Wandsworth Road.
1 year- £8.90 (Overseas yearly membership only. Europe £14.00) London SW3 4TE
For editorial material send to: The Editor, BEEBUG, P.O. Box 50, St. Albans, Herts AL1 1 AR
IF YOU OWN A BBC MACHINE, OR HAVEORDEREDONE,
OR ARE JUST THINKING ABOUT GETTING ONE, THEN YOU
NEED BEEBUG.
BEEBUG runsa regular magazine devoted exclusively to the BBC
Micro (10 issues per year).
Latest News on the BBC project.
What you should know before you order a machine.
New program listings, regular advice clinic, and hints and tips pages
in each issue.
April Issue: 3D Noughts and Crosses, Moon Lander. Ellipse and 3D
Surface.
Plus articles on Upgrading to Model B, Making Sounds, and
Operating System Calls.
May Issue: Careers. Bomber. Chords. Spiral and more. Plus articles
on Graphics. Writing Games Programs, and Using the Assembler.
June Issue: Mazetrap. Mini Text Editor. Polygon; plus articles on
upgrading. The User Port, TV set and Monitor review. Graphics part II,
More Assembler Hints. Structuring in BBC Basic, plus BBC Bugs.
July issue BEEB INVADERS and other programs - plus articles on
using the Teletext mode. BBC cassette bugs fix. Software Review, using
user defined keys. More on structuring in Basic. Using the User Port, and
many hints and tips.
VoxBox
the product that speaks for itself!
Speech adds a new dimension to computing
and the Mutek VoxBox, unlike most other systems,
gives the capability to generate unlimited vocabulary
speech from your computer. The unit is easily
programmed via a parallel or serial port and a
version is available for most popular computers. The
principle of phoneme synthesis is used and,
because phonemes are tne ''building blocks of
speech", all English words and a large number of
foreign language components may be easily
constructed.
An increasing range of software is available to
enable quick and easy sentence construction
The hardware is supplied complete and tested with
inbuilt power supply and connectors for your
computer.
Versions range from £65 for connection to PET,
Apple, TRS-80, Video Genie, OSI, UK101, VIC and
Acorn with no hidden extras for connecting leads,
free demonstration software and excellent
documentation.
Listen before you buy
We can honestly say the quality is nearly as good as
human speech, so why not call us after 6pm and
listen to our computer talking through VoxBox.
You may place a credit card order or a request for
further information after the message.
BUSS
BYTES
44 Fore St. Ilfracombe. Nth Devon. Tel: (0271 ) 62801
Mutek
Quarry Hill, Box, Wilts
Tel: Bath (0225) 743289
Acorn Dealers
Video Genie
Sales and
Service
Atom Micros
Acorn GP80 Printers
SeikoshaGPIOOA
Printers
Monitors -12" B/W
Monitors- 12" Green
5%" Disc Drives
(C/W P.S.U. & CASE)
BBC Micro
Service and
Information
Centre
BBC Upgrade Kits
BBC printer interfaces
5Va" Floppy Discs
C-12 Cassette Tapes
Cassette Recorders
Continuous Stationery
Software
Software
written to order
REPAIRS
& SERVICE
ACORN USER SEPTEMBER
55
COMPETITION
Solve the cyphers in Simon Daily's brainteaser and
you are well on the way to winning this month's
£20 prize of software.
ftamtmimM ^a0 rwa»^mvsnejm^9Wixa^M9^»mm
T
he advent of the computer age
has opened up vast new areas in the
field of codes and ciphers. A
computer's ability to perform millions
of operations slavishly and correctly
makes it an ideal tool for taking the
drudgery out of encoding and
decoding a language. Indeed,
looked at one way, a computer is a
natural cryptological machine.
Some codes, such as semaphore
or morse, have been developed, not
to ensure secrecy, but to facilitate
communications. Radio hams
sometimes convert text to and from
morse code with computers: if you
can interface your micro to a short-
wave radio you can have some fun
'eavesdropping' on the traffic.
The most famous example of a
computer-related code must be that
produced by the Enigma machine,
used by the German High Command
throughout World War II.
B
Jut at Bletchley Park in
Buckinghamshire a top-secret Allied
team was" merrily reading most of the
messages from mid-1940 onwards.
The resulting material - dubbed
'Ultra' - is now recognised as having
played a significant role in winning
the war.
Enigma consisted of interlinking
and individually settable wheels
(three to begin with), each of which
had 26 pairs of input/output leads,
wired differently for wheel one, wheel
two, etc. The operator would punch
the relevant letter on a 26-letter
keyboard and, via a tortuous route,
Enigma with the lid off . . . this Polish
reconstruction shows the wheels
which did most of the encoding, the
lamps which lit up the encoded or
decoded letter and the keyboard.
In the example on the left below,
each letter stands for one and only
one other letter. The starting point
is to analyse the frequency of the
letters. The subject matter of the
message, incidentally, was frequently
helpful in breaking into Enigma.
The example on the right below
is more complex, as it uses a
keyword. Thus, if your keyword is
'ACORN' and the word you're
encoding is 'Microcomputer', the
result is NLRJCDRBHIUHG, obtained
as follows: A is the first letter of the
alphabet; you therefore add one to
M to get N. C is the third letter, so
becomes L O is the 28th letter, etc.
Y
the signal would travel through the
wheels (and a few other things built
into this electronic maze) before
coming back to light up a different
letter on a glass-covered keyboard.
In this way a whole message could
be encoded and sent by morse to its
destination, where an identical
machine would decode it.
If you are a skilful programmer,
you could probably turn your micro
into a simulation of an Enigma
machine. On a BBC micro, the DEF
PROC statement might be useful in
setting up the input/output leads on
each rotor* For those less inclined
to embark on grandiose projects,
this month's competition features two
secret messages. Both can be
solved with pen and paper - but a
computer program should make it
easier.
ou have two clues from your
spies: at least four of the five-letter
words are suspected to be the same.
Second, the encipherer is known to
favour keywords of a literary bent -
'LEOTOLSTOr,
'WILLIAMSHAKESPEARE'.
One final aid - the spaces in both
messages are genuine.
Send your entries to the
Competition Editor by October 1 and
mark them 'Competition 2'. The first
three correct entries out of the bag
win £20-worth of Acornsoft
packages.
FOOTNOTE
*For details see Top Secret Ultra by
Peter Calvocoressi (Sphere), Ultra
Goes to War by Ronald Lewin
(Arrow) and, best of all, Cryptologla
vol 6, no 2 (Rose-Hulman Institute of
Technology, Terre Haute, Indiana
47803, USA) $
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VjTAOP OUR DRMSRM KRFOA VQKO VMTDQMS OAFMSV1P KARLV1K
ZVCRH3MT HRIV UJSVKGI3EV UJMS VQKGV1DP DJTAO OR HRSVIOOV
HQY3HFH OVHGVIQOFIV OUVMOP X 3EV SVTJVVK CVMOJT1QSV
KVEVMOP KVEVM XQAIVMAVJO
C1SS 3
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56
ACORN USER SEPTEMBER
Get the NEW
EPSON mh 111
Quickly. Cheaply
1111 lb K 1 1| because as one of The UK's largest
Epson distributors we have ample stocks.
In London, Birmingham, Manchester, Newcastle and
St. Ives (Huntingdonshire).
U II E II II I II because we move Epson's quickly,
and you are buying directly from the distributor.
Get it
See Westrexon
You can by contacting
Stand No
101
WestrexCo. Ltd.
Bilton Industrial Estate Fairway Drive
Greenford Middlesex UB6 8PW
Telephone:
London:
Birmingham:
Manchester:
Newcastle:
St. Ives:
01 578 0957
021 554 5827
061 764 0324
0632 326551
0480 66343
30+ PROGRAMS FOR
THE BBC MICROCOMPUTER
This Book contains program listings, with explanations
and tips on using the BBC Micro
GAMES UTILITIES GRAPHICS & MUSIC
'ASTRO RUN' 'FASTFINDER' '3D GRAPHICS'
Most programs will run on Models A & B
Edited by C.J.Evans, various Authors.
ISBN 946190 00 3
£5.00 inclusive of p&p
Cassette leads for the BBC Micro
The BBC Micro comes with an incomplete lead
7Pin Din to 2x3.5mm & 1x2.5mm minijacks £4.65(a)
7Pin Din to 5Pin Din & 2.5mm minijack £4.65(a)
7 Pin Din to 7Pin Din £4.65(a)
7Pin Din to 2x3.5mm minijacks (see XX) £1 50 (a)
7 Pin Din to 5 Pin Din (see XX) £1 .50 (a)
7Pin Din PLUGS Two for£ .65(a)
6Pin Din PLUGS(for RGB socket) Two for£ .65(a)
5PinDinPLUGS(360 forRS232) Two for£ .65(a)
XX These leads allow you to load and save but have no
remote facility
MONITOR/VIDEO LEADS
BNC Plus to Phono Plus
(i.e. BBC Micro to Rediffusion TVRM)
Full range of video leads in stock
£2.20 (b)
PRINTERS
STAR DP8480 FROM £228.85 inc VAT
80CPS : 80/96/1 32 COLS
BIDIRECTIONAL LOGIC SEEKING
CENTRONICS RS232
FRICTION FEED £199.00 £213.00
+29.85 VAT +£31.96 VAT
=£228.85 =£245.00
TRACTOR WITH £217.39
FRICTION FEED +£32.61 VAT
=£250.00
£246.09
+£36.91 VAT
=£283.00
(24HRSECURICOR DELIVERY FOR PRINTERS £6.00)
PRINTER CABLE BBC to 36way CENTRONICS TYPE
CONNECTOR £1 7.50(f)
PRINTER CABLE BBC to 25 WAY D TYPE
FOR USE WITH RS232) £9.50 (f)
RAM CHIPS
481 6 (1 00ns) As used in the BBC, 8 Chips gives 1 6k
£4.00 each (b)
Special offer 8 x 481 6 for £29.00 p&p free
21 1 4 As used in the Acorn Atom 20 Chips gives 1 0k
£1.20 each (b)
Programs for the BBC Micro wanted
A RANGE OF SOFTWARE CASSETTES
AVAILABLE SHORTLY
Send SAE for full price list
VAT Included where applicable
POSTAGE (a) 35p (b) 50p (f) & Book Free
Orders over £1 0.00 post free (Not applicable to printers)
C.J.E.
MICROCOMPUTERS
25 HENRY AVE, RUSTINGTON,
W.SUSSEX. BN16. 2PA (09062) 74998
ACORN USER SEPTEMBER
57
USER GROUP NEWS
Calling all
Atom fans
The Atom User Group started in
1980 as a result of discussions
between myself, then an under-
graduate at Cambridge and the staff
of Acorn. It is run as a part-time
enterprise by three people in
Coventry. We intend to provide a
newsletter four times a year, and to
provide a software library service, all
at basically the cost of organisation,
production and distribution.
Software in the library has been
contributed by members of the group,
and all members are encouraged to
contribute software and articles for
the newsletter.
Membership is around 1000
worldwide. The majority of members
are individuals, although there are a
number of schools. I feel the
education section is an area that
needs encouraging as it does not
seem to be well supported.
If you would like any more
information, contact: David Frost, c/o
18 Freshwell Drive, Potters Green,
Coventry.
Teachers unite
Muse is a national organisation of
teachers involved in schools
microcomputing. Members receive
our journal Computers in Schools four
times a year, and two special reports
on important and topical aspects of
microcomputers. The February 1983
report will consist of a comprehensive
review of the BBC micro and
peripherals. The next report
(September 1982) will deal with
interfacing microcomputers.
Regular meetings are arranged
and Muse is active in the
development and standardisation of
educational software. It supports an
extensive library of progams for
microcomputers. Other services to
members include microcomputer
(and video) insurance, and
concessions with equipment suppliers.
Membership fee is £10 and forms
can be obtained from Muse.
Freepost, Bromsgrove, Worcestershire
B61 7BR.
And the rest
■The BBC (National) User Group
holds monthly meetings: has a free
software library, and issues a
monthly news-sheet: Discounts
arranged on printers, disk drives, and
other hardware. Membership £8 a
year payable to the Group. Contact: J.
Craig, 40 Mount Pleasant Avenue,
Wells, Somerset BA5 2JQ
■Abug stands for Atom/BBC User
Group. Meetings are on second
Wednesday of every month at
premises of Superior Systems Ltd,
178 West Street, Sheffield from 6.30-
8.30 pm. Contact Steve White at
(0742) 755005
■ Beebug have asked us to inform
readers that the club is run by
Sheridan Williams and David Graham.
Anybody else out there? Contact Acorn User, 53 Bedford Square, London WC1
USER GROUP LIST
Mr J. Ashurst
Acorn Computer Users Group
Abraham Moss Centre
Crescent Road
Manchester 8
Mr P. Beverley
Norwich Area Acorn User Group
Room 12a
Norwich City College
Ipswich Road
Norwich NR2 2LL
Mr B. Carroll
The Cottage
42 Manor Road
Aldershot
GU11 3DG
Mr M. Christiansen
BBC Users Group
Marienlystveien 2 - Stavne
N-7000 Trondheim
Norway
Mr J. Craig
National BBC User Group
40 Mount Pleasant Avenue
Wells
Somerset
BA5 2JQ
Rupert Steele
Amateur Computer Club
St John's College
Oxford OX1 3JP
Mr D.L. Evans
23 Hitchin Road,
Hentow Camp
Bedfordshire
Mr J. Price
Bedford House
27-28 St George's Road
Brighton
Sussex
Mr T. Sharpies
Laserbug
4 Station Bridge
Woodgrange Road
London E7 ONE
Mr C. Rutter
Medway Atom Users Group
St John Fisher School
Ordnance Street
Chatham
Kent
Mr P. Frost
Atom User Group
18 Frankwell Drive
Potters Green
Coventry CV2 2FB
Robin Bradbeer
Association of London
Computer Clubs
Polytechnic of North London
Holloway
London N7 8DB
MrT.G. Meredith
Acorn Atom User Group
Sheerwater,
Yealm View Road
Newton Ferrers
South Devon
Mr CM. Rutter
Manchester Atom Users' Group
3 Leopold Avenue
Withington
Manchester M20 8JG
Mr R. Luff
Kingbee
54 Arlington Close
Kingswinford
West Midlands
Steve White
Atom/BBC User Group
c/o Superior Systems Ltd
1 78 West Street
Sheffield
Tel: (0742) 755005
N.P. (Bazyle) Butcher
Harrow Computer Group
16 St Peter's Close
Bushey Heath
Watford WD2 3 LG
Richard Green
Muse
22 Tennyson Avenue
Hull HU5 3TW
58
ACORN USER SEPTEMBER
ATOM GRAPHS
Tr
his program aims to provide a
means of displaying experimental
data graphically. The data
represented on the graph can be
inspected and then, if appropriate,
it can be approximated to a straight
line, the gradient and intercept
being calculated by the method of
continued page 63^
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180 P."?. EET SIZE OF DIVISION MARKS"
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ACORN USER SEPTEMBER
59
LETTERS
_^— — T^e *****
^e5v—;^.., 3 pressed-^
•-;;;-::■/•;. .. ; -.,.^
do& wu \, pxpatisi 011 ^
W* ? - SfT*» „ \3 of * e
n -p no - Ls -" ,-• .'his - ave -,-•■ .aw
ttsies
- c
i& i
The buzz from the
more pronounced
speaker is
on some
machines than on others. It can
be stopped most simply by fitting
a plug into the 1MHz expansion
bus and on this plug fitting a
resistor between pin 16 and pin
18. The resistor should have a
value of 10k ohms. Alternatively
a similar resistor can be soldered
to the printed circuit board
between the appropriate tracks.
The modification to reduce the
level of this buzz is being
included in the next issue of the
printed circuit boards.
The Econet expansion as well
as the disc internal expansion and
the speech synthesis internal
expansion are all additional
rather than being fitted as
standard on the Model B.
Some machines have been
supplied with the operating
system in EPROM in the sockets
that you mentioned. In other
machines four EPROMs are
replaced by a single ROM. This
does not affect the performance of
the machine in any way.
The BBC disc system does not
have a regulated power supply.
The switch mode power supply on
the BBC microcomputer is able to
run the discs as well as the
computer itself. If such a power
supply was not fitted Initially
then the dealer will fit this as
part of the disc upgrade. If you
wish to have your model B
subsequently upgraded to Include
a disc interface then the dealer
will do this and will probably
charge in the region of £80 or
£90. The single disc drive itself
costs £.265.00.
■•:
here but r ir °^ fauhf plea3 *l
but
**& soon
With ,i_
here
and
at the J"' cr 'ey are an l° nJto ^s
ha
'•Hi
--.
*f
not
Cor '^W
,^«ec; I m„„ '^ mat
?*« Can ,
Here are a few comments that
may help you to plan for the
future. It is quite possible to put
a large number of disc systems on
the network and as there are very
clear advantages in a network
system we would encourage you
in that direction. For example
with a network all the users can
share one or more expensive
printers.A network would enable
the teacher to see what each
person is doing without having to
actually walk around and can also
be used over a considerable
distance as a message service.
However, if you do find that
you can afford a large number of
disc systems then there is
absolutely nothing to stop you
In stalling those alongside the net.
Any one or more other disc
systems can act as a file server or
of course they can be used
individually.
60
ACORN USER SEPTEMBER
■•■■ '-''• ,;"
■^:-'
r.l W
H bail* wa«
:,!
bo uw*"**l Xt * —
wvarf" ■■-"■ ■■ ... ..••■'-■■- ■
-;,.., •T-V, ::■,.,■:.■■--■ ■'-=■'■"■
,,-,„-.. ...
■
-
etc ew. "
■. ■ ■■
.sxsr- ■■■■-<*-
Quae apart from Lhe fhtiurfc
\:> ■■:r J '^ ':v>::' + ?.— v T :
6rop' + :*Sesa they also fwi; -
■- - ■ .. :-/'-.
wh&r. h»a g>ne wrong, ex* •...
and exactly how xLc&ntepu*. ry:."
volume lew roi -:y set, for
*jxan,[.-. ■ ■■•' -- ■ uM rwul
'turn up volume' or *tuni down
tf I ;:>. to '!/
oompuw jargrm ihe error roafieaflre
ft tap* raisin? are
H I n ■ i : I ::■ .:. T - M*J le tfuu an
enUre oassaus file ehcu^d tr
ied ae ue#«8 due ic & fa
n sr* pom:. It should at jtor e
Ibte ir» read ui ihe ffol 1 ks, i^
neoftfiaa^' nr^^rtf tU* low «c ;
v ■
.-
■'-,
£*SE ■■■■ 5."
W« are sorry to hear of the
trouble yon lurvr dobq hiving
over readbsck from your cassette.
We Futvts passed your complaint-*
on to Acorn Computers who have
euggested that their cassette
filing eyitem progrsm mey be of
help to yon-
/
'•-;•
■:
'■•■
.--,
°^,
. *BC
'f»T L
5* .
■^,.
We must apologise to ell the Atom
users who felt that we gave too
much epaoe to the BBO micro in
the first Issue* We hav* Included
several items epeclflcally for
Atom users in this Issue and plan
to continue to do eo. On page 3a
we publish details of the BBO
BASIC Board for the Atom. This
will enable Atom owners to run
most software for the BBC micra !
ooi their Atoms. However,
programs must be typed in, they
cannot be run from cassette. See
page 3fi\
i OS
"■*' :
i.' -m* ■■■■
jAaMh-
LETTERS
CASSEUE FILING SYSTEM
A numtwr ol 3hortcominQ5 in Ihe
machine operating sysicn version
01 tor Ihe BBC micro have come
lo lighi This article provides details
of iwo useful modifications thai can
to applied by user* to itieir own
machines
Perhaps the two most signihcanl
problems with Ihe machine
operating system are concerned
wiin iho casselle Ming system. The
first involves ihe character output
routines w»thin the operating
system whereby complete Basic
strings are sometimes not written to
the tape. The second is caused by
a hardware problem which corrupts
certain files as they are written to
the tape This prevents me Me
being input Mck into the computer
A sollware modification to
remedy these problems has been
devised by Richard Russell of the
BBC and nps been evaluated by
Acorn So far as it is possible to
ascertain. Ihe prescribed change
overcomes these difficulties
For the technically minded,
detailed descriptions of the
problems are given here In the f<tsl
case the cassetie OSBPUT routine
sometimes alters ihe processor's A
register when this should be
preserved, tl this occurs when
Basic is outputting a string In a
PfltNTs statement, the characters o*
the string will not be sent to the
tape Thrs win then be detected
dunng use of a subsequent
INPUT* statement at which poini a
type mismatch error will occur
The second problem is caused
by the corruption of the first byte ol
a block on (ape. Since this contains
block header information, the block
iisetl cannot be read back. One
particular manifestation of Ihis is
that a program SAVEo af 1200 bits
per second may not subsequently
be LOADabie
The modification »s given beiow
as a program to be typed into the
BBC micro and RUN on startup H
contains a *KEY command in line 9
10 ensure Ihe modification is
preserved over use ol Ihe BREAK
key Obviously, the modification is
lost from memory il power is turned
eft and also on a hard reset' (rapid
BREAK BREAK). Having installed
the modification it might be a good
plan to SAVE il on the front of a
tape to be LOADed whenever the
computer is started up.
ACOftW US£* SEPTEMBER
6t
Whether you would like to
have a question answered
or just to air your views, write
to us at Acorn User, 53
Bedford Square, London
WC1B 3DZ. The Editor
reserves the right to amend
or alter any letter prior to
publication.
The information that is
transmitted on the teletext pages
is in fact in Basic and not in
machine code hut a number of
special symbols are used to mark
particular characters such as the
end of line character. It is not
possible to type into the computer
what you see on the screen. The
special codes have to be de-coded
by the BBC teletext unit which
works with the BBC Micro-
computer System. It is not
possible to use a normal teletext
television in any way at all to get
teletext into the BBC Computer
System. The only way that one
can receive telesoftware directly
to the BBC Microcomputer is with
the special unit mentioned above.
LET ACORNSOFT OPEN THE
DOORS TO
YOUR IMAGINATION
BBC Microcomputer or Acorn Atom
Acornsofc is the software
division of Acorn Computers,
designers and manufacturers, of the
BBC Micro and Atom. We know
better than anyone che capability of
the machines, we know how
to get the very best from the
hardware. And we have
produced a range of exciting
games, exacting business and
useful household software.
The Biggest Range Available
Acornsoft software ranges
from authentic arcade games like
Snapper to Algebraic Manipulation
to Desk Diary to other languages like
FORTH and LISP. Striking colour,
amazing sound effects and powerful
graphics are all used to the full. And it
does not stop there. There is a
complete range of manuals,
accessories and plug-in ROMs.
Free Brochures
Just clip the coupon or write to
us and we will rush our catalogue
absolutely free. Can't wait for the post
ring 01-930 L614
now! Don't delay —
do it today. Let Acornsoft help you
get the best from our machine and
open the doors to your imagination
Acornsoft and Atom arc registered
trade marks of Acorn Computers Ltd.
>1C0RNS£FT
4A Market Hill.
CAMBRIDGE CB2 3NJ.
Please rush me mv free
literature from Acornsoft.
□ Atom OBBC Plca*Mick
Name
Address
L£
Postcode
I
I
J
62
ACORN USER SEPTEMBER
DEALER LIST
Official Acorn
Dealers
in the U.K.
Acorn dealers stock and service the Atom computer/ Acorn systems and Acorn
softsoftware. Many also offer service facilities for the BBC micro and these are
marked with an asterisk. The Acorn dealer not only sells computers and peripherals
but provides vital customer support. Most have recently attended technical
seminars in Cambridge to ensure that they deal effectively with customers'
enquiries* In addition, Acorn supply dealers with specific test and diagnostic
equipment to speed fault finding*
LONDON
f a,?rO'S- Sj'.'i El
01-24 7 3453
0^*26 9392
*Cewe oi Souna wi i
01-727 0511
0* 505 7724
•Micro Sto*e$W3
01-3*2 9291
*0*t Record* SWn
01-223 7730
Pay. £iec;r»ca' SA20
oi *v es^e
PA J Rcn-Ul U4 NW4
01 368 0572
REW Wei! End Video Cerwe WC?
01440 3 »6 '?
PAe^ieyLiaSE26
01-693 ISIS
•Te^ro-rahc UONW'O
01-723 C233
TheV.oeoPaace*V8
01-937 35^7
BIRMINGHAM
Qua Hy R«3ic & Tfif^sion Co &1 4
02 1 -444 2889
TyDOAiiier Centre E'3tft9H>rM B53
021-382 '85
*yi>Mnler C«->!r* 'H*m G«>C6lB5
02i 622 5385.7
T>*&e*trTe Ce^J^'Duorcf Road* 9i8
021 455 9n "
Tyst writer CefweiKi^sHeairN 3*4
021444 73*19
AVON
"M-Cros tyte 6*Tti
0225-334659
BEDFORDSHIRE
'9'cac*a> Ei-aci-onicaaoBedfo-a
023 -J 213639
BERKSHIRE
•W*i\ds*> Computer Cent*
0753556077
■ A - ■; ■ -
BUCKINGHAMSHIRE
A LWrieeicLtc Gr©a: Missenoerv
024 06 2560
*Ta*3ce Ud tvertdove*
0296 623915
Hi-Vw Electron*!;* wctvewn
09083^2808
CAMBRIDGESHIRE
•A'den Personal Comouie-s
Pe^fCcoug" 1
0733*47767
'Camonoge CofriDu'e* 5to^
CdfnDf+Cc*
0223^653j4
*Conif 0' UAf-ve'sat Ca^D'*dge
0223 358757
CHESHIRE
Be'ta^d Eiecifo^cs Lid UDion
0244-360123
"NO'in^m Computer* YVa'rirr^Jon
0928 35i 10
CLEVELAND
•Ciiliomnea Etect'onies Lid
V : ■■^r -■ ..■:■
Q642 2J7727
CORNWALL
*6'ewef6 Bi-nr»ey Cam&O'ne
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► continued from page 59
least squares * There are two main
advantages of using the Atom
instead of a programmable
calculator First, the scatter of
points either side of the best
straight line can clearly be seen, so
any general trends can be noted
and individual points, which may
be suspect, can quickly be
identified- Second, data can easily
be added, deleted, or amended,
and the effect on the best straight
line can then be seen and/or
calculated, (The graph is auto-
matically re-ranged every time the
data is changed, so that it fits
exactly onto the screen.)
The structure of the program is
such that after entering an initial
set of pairs of X and Y values, the
user is given menu:
• input more points
• check values already entered,
• change certain values.
• plot points only.
• calculate gradient and intercept
• calculate gradient for Y=MX.
• plot points and draw best fit line.
• delete certain points.
c "I^^^H
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• set size of division marks for
axes.
• restart.
The program should be entirely
self-documenting, and no problems
encountered during running,
provided you follow the general
rule: // in doubt - press the return
key. If you are being asked to input,
delete or change anything, and you
don't want to, just press return.
The program was written to run
in a fully-expanded Atom (12k+12k)
but if you only have 3k in the
graphics memory, you could
change line 30 to H=185; W-121;
J=3 (or even with 1 Vfek - H=90;
W=121; J=3).
A bare listing of the program is
provided, but for a fully annotated
listing plus a cassette of the
program send £1.50. to Mr P.
Beverley, Department of Electronics
& Electrical Engineering, Norwich
City College, Ipswich Road,
Norwich, to whom comments and
criticisms should be sent - they
would be much appreciated.
"Practical Physics by G.L Squires,
McGraw-Hill, ISBN 070940703. f
ACORN USER SEPTEMBER
63
THERE'S ONLY ONE THING
THAT CAN HELP YOU TO GET
THE BEST OUT OP YOUR
BBC MICRO
The only non-commercial independent
national BBC Microcomputer user group
Please enrol me as a member :' LASERBTJG
I enclose a cheque/PO for £12.00 for 12 months subscription.
Name
Address
Tel
P'.ease make all cheques/PO payable to LASERBUG and send to
4 Station Bridge Woodgrange Road Forest Gate London, E7 ONE
ADVERTISERS INDEX
Acorn inside back cover
Acornsoft 30, 62
Addison-Wesley 47
Anglia 7
BBC Basic 40
Beebug 55
Bits & Byte 55
C. J. E 57
Cardiff Micros 43
Computer Concepts 17
Computers for All 5
3D Computers 40
Control Universal 39
Earlcape 35
Electronequip 39
Eltec 12
Emprise 43
Golem 18
I. J. K. Software (Sinclair) 18
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Leaselink Viewdata inside front cover
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Program Power back cover
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i f-\ r
Q'Tek 12
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T Shirt Offer 48
Technomatic 9
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Westrex 57
Windsor Computer Centre 43
A bigger range than the
Himalayas
k<
The Acorn Atom From £ii8 plus vat.
W**-M rf
aSKteR-f-^,
Personal Computing -Instructional
and Fun
To get the best out of the personal
computing you need two things -
hardware that is powerful and reliable
-software that uses the hardware to
the full. The Atom range is just that.
The Atom -tried and tested
The Atom was designed to last -
inside and out. Outside a rugged, high
impact case with a proper keyboard.
Tested to withstand children as well as
adults. Inside a powerful operating
system that will never be bettered.
It is available in several versions so you
can choose what you want. And there
is an enormous range of additional
boards that fit inside the casing -start
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more versatility when you need it
The Accessories -something for
everyone
Diskpacks, printers, monitors,
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languages, arcade-type games,
business and household software.
Whatever you want to do - teach your
children, run your business -you can't
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Available Nationwide
Not just mail order, the Atom
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dealer network -they will help and
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Acorn Compuiers Limited.
Fulbourn Road, Cherry
Hmton, Cambridge CB1 4JN
Tel: (0223) 245200.
FREE Catalogue
For full details of the
fill in the coupon
or write to us.
| To: Acorn Computers Ltd, ~~" -J
Fulbourn Road. Cherry Hmton,
| Cambridge CB1 4JN Tel: (0223) 245200.
Please rush me a complete list of the
Atom range.
Name
Address .
^■MCORN
COMPUTER
Postcode
:J
DQE0QQOQEQQOOOQQEQ0QGO
V
2
L W A
NEW -DEVASTATING MODEL B (or 32K MODEL A) GAME
FROM BRITAIN S LEADING SOFTWARE HOUSE !
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t*o*
MODEL B (or 32K MODEL A)
Timelrek
The ultimate 'real-time' Startrek, with Battle Zone
indecision your main enemy. Brilliant colour and sound,
'One— screen' presentation. Twenty skill levels. Panic
Button for 'once-only' space leap. Torpedosight control. A
programming masterpiece!! 1.7. 95
Eldorado Gold
Welcome to a past age, when cowboys ruled the roost and
Indians terrorised the new settlers. In ELDORADO
COUNTY many fortunes were made -and nearly as many
lost! Legend has it that Old Bill McCluskey, who met a
rather sudden death, had built up a vast treasure
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man where many have failed? If the marauding Apaches or
Big Jake's gang don't get you, you may die of thirst in the
desert or starve to death in jail. £6,95
World Geography
Beautifully drawn HI RES colour map and graded testing of
world capitals and populations, makes learning
geographical facts a pleasure. 160 countries covered in
total. Pin-pointing of each location in turn aids general
awareness- €5.95
Space Maze
You have crash landed in the legendary labyrinth of Titan,
inhabited by alien monsters known as 'Froogs'. Find your
way out to the 'Transmat* probe before being cornered and
eaten. Eight skill levels and 3D colour graphics. £5.95
Deduct £1 per cassette
when ordering two or more.
Astro Navigator
Navigate your way through a variety of treacherous
caverns, inhabited by killer rockmites. Avoid the dangers
with your climb, dive, reverse and thruster controls. 5 Skill
Levels Top 5 scores ranked. Excellent colour graphics and
sound in this exciting 'real-time' game. £4.95
MODEL A or B
Chess
High quality chess game with castling, 'en passant', play
black or white, rejection of illegal moves and six levels of
play. Set up problem games. £7,95
Micro -Budget
Proven personal finance program which enables you to
record, review, analyse and budget your income and
expenses for twelve separate monthly periods. Coding
system gives sub-totals, selective summary of entries and
cumulative cash flow. All figures can be saved to tape. £6.95
Munchyman
Colourful and highly entertaining version of this popular
arcade game. Munch your way to a high score, before the
'munchers' devour you. Reverse roles by munching the
stars. The more you score, the harder the game gets. £5.95
Other programs available:
Start rek £5.95/Gomoku £3.95/Disassembler £5.95
Cat & Mouse £4.95/Zombies (New) £3.95
Acorn
ATOM
We are now an authorised
Acorn Dealer. Send for our
catalogue on special hardware
deals, plus over 60 Atom
programs currently held in
stock
H/£
73
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Please add 55p
order P & P
+ VAT at 15%
IMICRO POWER LTD.
8 8a REGENT STREET
CHAPEL ALLERTON
LEEDS LS7 4PE.
Tel. [0532] 683186
73
5
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GQHEQaOQSSGQOOQQSQaQQQ
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